Timing control unit for controlling an illumination device with coherent light source

ABSTRACT

An illumination device has a coherent light source that emits coherent light beam, and an optical device that diffuses the coherent light beam, wherein the optical device comprises a first diffusion region that diffuses the coherent light beam to illuminate a first area, and a second diffusion region that diffuses the coherent light beam to display predetermined information in a second area.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/523,007, filed Apr. 28, 2017, which is the National Stage entry ofInternational Application No. PCT/JP2015/081373, filed Nov. 6, 2015,which designated the United States, the entireties of which areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to an illumination device that illuminatesa predetermined area using coherent light beam.

BACKGROUND OF THE INVENTION

Techniques are known in which illumination equipment such as streetlamps, room lighting, cameras and the like can illuminate only a desiredplace using a cylindrical lens, an actuator, a shade, etc. (see PatentLiterature 1 and 2).

CITATION LIST Patent Literature

Patent Literature 1: Japanese Patent No. 3586213

Patent Literature 2: Japanese Patent No. 5293893

SUMMARY OF THE INVENTION Technical Problem

This type of conventional technology keeps in mind the fact that aposition relatively near illumination equipment is illuminated on aspot, and a position far from the illumination equipment cannot beilluminated. In addition, conventionally, since it is merely focused onilluminating, decorative lighting and an illumination mode at arbitraryplaces cannot be switched at arbitrary timing.

The problems to be solved by the present invention are to provide anillumination device which can arbitrarily change the illumination modewithout complicating the configuration of an optical system.

Solution to Problem

In order to solve the above problem, a first aspect of the presentinvention provides an illumination device including a coherent lightsource that emits coherent light beam; and an optical device thatdiffuses the coherent light beam, wherein the optical device comprises afirst diffusion region that diffuses the coherent light beam toilluminate a first area, and a second diffusion region that diffuses thecoherent light beam to display predetermined information in a secondarea.

The illumination device may include a scanning unit that scans thecoherent light beam emitted by the coherent light source on the opticaldevice, wherein the first diffusion region may diffuse coherent lightbeam from the scanning unit to illuminate the first area, and the seconddiffusion region may diffuse the coherent light beam from the scanningunit to display the predetermined information in the second area.

The second diffusion region may display the information by changing atleast one of hue, brightness, and chroma in the second area.

The second diffusion region may display the information including atleast one of a picture, a pattern, a character, a number, and a symbolin a single color or in a plurality of colors.

The first area and the second area may be arranged so as not to overlapone another.

The first area and the second area may be arranged so that at leastparts of the first area and the second area overlap one another.

The scanning unit may scan the coherent light beam on the firstdiffusion region and the second diffusion region.

The first diffusion region may have a plurality of first elementdiffusion regions and the plurality of first element diffusion regionsmay diffuse incident coherent light beams and illuminate respectivepartial regions.

The second diffusion region may have a plurality of second elementdiffusion regions and the plurality of second element diffusion regionsmay diffuse incident coherent light beams and display the diffusedcoherent light beams on respective partial regions.

The scanning unit may include a light scanning device that periodicallychanges a traveling direction of the coherent light beam emitted fromthe coherent light source.

The illumination device may include a timing control unit that controlsan incident timing of the coherent light beam on the optical device orcontrols an illumination timing in the first area and a display timingin the second area.

The illumination device may also include a timing control unit thatcontrols whether or not to scan the coherent light beam from thescanning unit on at least one of the first diffusion region and thesecond diffusion region.

The illumination device may include an object detection unit thatdetects an object in a predetermined area, wherein the timing controlunit may control a scanning timing of the coherent light beam in atleast one of the first diffusion region and the second diffusion region,in accordance with a position of the object detected by the objectdetection unit.

The timing control unit may control the scanning timing of the coherentlight beam in the first diffusion region so that the object detected bythe object detection unit is illuminated in the first area.

The timing control unit may control the scanning timing of the coherentlight beam in the first diffusion region so that the first area ispositioned in a region where the object detected by the object detectionunit does not exist.

The illumination device may include an event detection unit that detectsan occurrence of a specific event, wherein the timing control unit maycontrol the scanning timing of the coherent light beam in at least oneof the first diffusion region and the second diffusion region when it isdetected by the event detection unit that the specific event hasoccurred.

The coherent light source has a plurality of light emitting units thatemit a plurality of coherent light beams having different emissionwavelength ranges, and at least one of the first diffusion region andthe second diffusion region may have a plurality of diffusion regionparts to be scanned by the plurality of coherent light beams.

The optical device may be a hologram recording medium, and the firstdiffusion region and the second diffusion region may have elementhologram areas in which different interference fringe pattern areformed.

The optical device may be a lens array group having a plurality of lensarrays, and the first diffusion region and the second diffusion regionmay include the lens array.

The optical device has a hologram recording medium and a lens arraygroup having a plurality of lens arrays, and one of the first diffusionregion and the second diffusion region may have the hologram recordingmedium and the other may include the lens array group.

The timing control unit may control a timing at which the coherent lightbeam from the scanning unit is continuously scanned on the firstdiffusion region, and the coherent light beam from the scanning unit isscanned on the second diffusion region.

The illumination device may include an information selection unit thatselects the information to be displayed in the second area, wherein thetiming control unit may control a timing at which the coherent lightbeam from the scanning unit is scanned on the second diffusion regionbased on the information selected by the information selection unit.

The illumination device may include a route information acquiring unitthat acquires route information for traveling, wherein the informationselection unit may select the information to be displayed in the secondarea based on route information acquired by the route informationacquiring unit.

The information selection unit may select the information capable ofdiscriminating at least one of a direction to travel and a direction notto travel based on the route information acquired by the routeinformation acquiring unit.

The information selection unit may select the information of a displaymode capable of discriminating one candidate route to travel among aplurality of candidate routes and the other candidate route.

The information selection unit may select information for displaying onecandidate route to travel among the plurality of candidate routes andthe other candidate routes using different colors.

The illumination device may include a map information acquiring unitthat acquires map information around a current position, and theinformation selection unit may select the information around a currentposition based on the map information acquired by the map informationacquiring unit.

An optical path length of the coherent light beam from the opticaldevice to the first area may be longer than an optical path length ofthe coherent light beam from the optical device to the second area.

The illumination device may include a beam diameter expansion memberthat expands a beam diameter of the coherent light beam, and an opticalshutter that switches the transmittance of coherent light beam incidenton the optical device or coherent light beam diffused by the opticaldevice, wherein the optical device has a plurality of element diffusionregions that respectively diffuse coherent light beam having a beamdiameter widened by the beam diameter expansion member, the opticalshutter has a plurality of element shutter units corresponding to theplurality of element diffusion regions, and the plurality of elementshutter units may switch a transmittance of coherent light beams to beincident on respective element diffusion regions or coherent light beamsdiffused by respective element diffusion regions.

The optical shutter may disposed closer to the optical device on a frontside of an optical axis than the optical device, and the plurality ofelement shutter units may switch a transmittance of coherent light beamsincident on respective element diffusion regions.

The optical shutter may be disposed closer to the optical device on arear side of an optical axis than the optical device, and the pluralityof element shutter units may switch a transmittance of coherent lightbeams diffused from respective element diffusion regions.

The optical shutter may switch an illumination mode for partial regionsin a predetermined illumination area illuminated by the plurality ofelement diffusion regions by individually switching the plurality ofelement shutters.

The illumination mode may be an illumination intensity for the partialregion or whether or not to illuminate the partial region.

The coherent light source may have a plurality of light source unitsthat emit a plurality of coherent light beams having different emissionwavelength ranges, the optical device may have a plurality of diffusionregions provided corresponding to the plurality of coherent light beamsand including the first diffusion region and the second diffusion regionto which the corresponding coherent light beam is incident, theplurality of diffusion regions may have the plurality of elementdiffusion regions, and the optical shutter may have the plurality ofelement shutter units corresponding to the plurality of elementdiffusion regions for the diffusion region.

The optical shutter may switch an illumination color of a whole area ofthe illumination area by switching the plurality of element shutterunits provided for the diffusion region as one set

The optical shutter may switch an illumination mode for the partialregion in the illumination area illuminated by the plurality of elementdiffusion regions by individually switching the plurality of elementshutter units provided in the plurality of diffusion regions.

The illumination mode may include an illumination color for the partialregion.

The optical shutter can switch a transmittance of the coherent lightbeam with a beam diameter enlarged stepwise or continuously, and theplurality of element shutter units may individually switch an incidentlight amount of coherent light beam to a corresponding element diffusionregion or a transmitted light amount of coherent light beam diffused ina corresponding element diffusion region.

The optical shutter may be a mechanical shutter, an electronic shutteror a multi-cell shutter.

The imaging device shutter may be a liquid crystal shutter that has aplurality of liquid crystal cells corresponding to the plurality ofelement shutter units, and may switch the transmittance of the coherentlight beam incident on a corresponding element diffusion region or thecoherent light beam diffused by a corresponding element diffusionregion.

The coherent light beam diffused in the first diffusion region of theoptical device may illuminate the first area, and the first diffusionregion may have the plurality of element diffusion regions.

Coherent light beam diffused in the second diffusion region of theoptical device may display predetermined information in the second areaand the second diffusion region may have one or more element diffusionregions.

The illumination device may include a driving unit that moves theoptical device, wherein the optical device may hold a plurality ofdiffusion regions including the first diffusion region and the seconddiffusion region, the driving unit may move the optical device such thatthe plurality of diffusion regions sequentially reach an illuminationposition of coherent light beam from the coherent light source, theplurality of diffusion regions may illuminate respective partial regionsin a predetermined illumination area by diffusion of the incidentcoherent light beam, and at least parts of the partial regionsilluminated by each of the plurality of diffusion regions may bedifferent from each other.

The illumination device may include a timing control unit that controlsan incident timing of the coherent light beam from the coherent lightsource on the optical device or an illumination timing in theillumination area.

The driving unit is configured to continuously rotate the optical devicein a rotation direction. The plurality of diffusion devices may bearranged along the rotation direction.

The optical device may have a disc shape.

The optical device may have a cylindrical shape.

The optical device may have a set of rotating rollers rotatable aboutrespective axes, and a belt-like portion wound around the pair ofrotating rollers in a loop shape, wherein the plurality of diffusiondevices may be arranged along a longitudinal direction of the belt-likeportion, and the driving unit may be configured to continuously rotateat least one rotating roller about an axis thereof.

The plurality of diffusion devices may have an elongated shape extendingin a direction perpendicular to a moving direction of the opticaldevice, and the coherent light source may have a laser array arranged ina direction perpendicular to the moving direction of the optical device.

The illumination device may include an object detection unit thatdetects an object existing in a predetermined illumination areailluminated by the optical device, wherein the timing control unit maycontrol an incident timing of the coherent light beam from the coherentlight source on the optical device or an illumination timing of theillumination area so that a region of the object detected by the objectdetection unit and the other region in the illumination area areilluminated in different illumination modes.

The object detection unit may include: an imaging device that images aninside of a predetermined illumination area illuminated by the opticaldevice; and an image processing unit that performs image processing onan imaging result of the imaging device and recognizes an object in thepredetermined illumination range illuminated by the optical device.

The object detection unit may include: a position information acquiringunit that acquires position information of a car in which theillumination device is disposed; a storage unit that stores the positioninformation of the object; and an information processing unit thatrecognizes the object in the predetermined illumination area illuminatedby the optical device based on the position information of the caracquired by the position information acquiring unit and the positioninformation of the object stored in the storage unit.

The illumination device may include a handle rotation detection unitthat detects rotation of a handle wheel of a car in which theillumination device is disposed, wherein the timing control unit maycontrol an incident timing of the coherent light beam from the coherentlight source on the optical device or an illumination timing of theillumination area based on rotation of the handle detected by the handlerotation detection unit.

The illumination device may include: an operation monitoring unit thatmonitors the operation of the scanning unit; and an auxiliaryillumination unit that illuminates a predetermined illumination areailluminated by the optical device when an abnormal operation of thescanning unit is detected by the operation monitoring unit.

The auxiliary illumination unit may include: an auxiliary mirrordisposed in an optical path between the coherent light source and thescanning unit when abnormal operation of the scanning unit is detectedby the operation monitoring unit; and an auxiliary optical device thatdiffuses the coherent light beam and illuminates the illumination area,and the auxiliary mirror may cause the coherent light beam from thecoherent light source to be incident on the auxiliary optical device.

The auxiliary optical device may illuminate the entire region of theillumination area by diffusion of the incident coherent light beam.

The auxiliary optical device may be a hologram recording medium.

The auxiliary illumination unit may include an auxiliary mirror disposedin an optical path between the coherent light source and the scanningunit when abnormal operation of the scanning unit is detected by theoperation monitoring unit, and the auxiliary mirror may cause thecoherent light beam from the coherent light source to be incident on theoptical device.

The auxiliary illumination unit may have a light source different fromthe coherent light source.

Another aspect of the present invention provides an illumination deviceincluding: a coherent light source that emits coherent light beam; abeam diameter expansion member that expands a beam diameter of thecoherent light beam; an optical device that diffuses coherent light beamhaving a widened beam diameter to illuminate a predetermined area; andan optical shutter that switches the transmittance of coherent lightbeam incident on the optical device or coherent light beam diffused bythe optical device, wherein the optical device has a plurality ofelement diffusion regions that respectively diffuse coherent light beam,the optical shutter has a plurality of element shutter unitscorresponding to the plurality of element diffusion regions, and theplurality of element shutter units switches a transmittance of coherentlight beam incident on a corresponding element diffusion region orcoherent light beam diffused by a corresponding element diffusionregion.

Still another aspect of the present invention provides an illuminationdevice including: a coherent light source that emits coherent lightbeam, a diffusion unit that holds a plurality of diffusion elements thatdiffuses the coherent light beam, and a driving unit that moves thediffusing unit so that the plurality of diffusing devices sequentiallyreach an illumination position of the coherent light beam, wherein theplurality of diffusion elements illuminate respective partial regions ina predetermined area by diffusion of the incident coherent light beam,and at least parts of the partial regions illuminated by the pluralityof diffusion devices are different from one another.

Still another aspect of the present invention provides an illuminationdevice including: a coherent light source that emits coherent lightbeam, a diffusion device that diffuses the coherent light beam andilluminates a predetermined area; an optical scanning unit that scansthe coherent light beam from the coherent light source on the diffusingdevice; an operation monitoring unit that monitors an operation of theoptical scanning unit; and an auxiliary illumination unit thatilluminates the predetermined area when an abnormal operation of thelight scanning means is detected by the operation monitoring unit,wherein the diffusion device has a plurality of element diffusionregions, the plurality of element diffusion regions illuminaterespective partial regions in the predetermined area by diffusion ofincident coherent light beam, and at least parts of the partial regionsilluminated by the plurality of element diffusion regions are differentfrom one another.

Advantageous Effects

According to the present invention, it is possible to provide anillumination device that can arbitrarily change an illumination mode ofan arbitrary area in an illumination area without complicating theconfiguration of the optical system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a schematic configuration of an illuminationdevice according to a first embodiment of the present invention.

FIG. 2 is a view showing a light scanning device.

FIGS. 3A and 3B are views showing specific examples of a hologramrecording medium.

FIG. 4 is a view showing an example in which a first area and a secondarea overlap.

FIG. 5 is a view showing a schematic configuration of an illuminationdevice according to a second embodiment of the present invention.

FIG. 6 is a view showing how a laser beam diffused by an optical device3 is incident on an illumination zone.

FIG. 7 is a view showing an example in which parts of rectangularillumination areas in a first area overlap with each other.

FIG. 8 is a view showing an example in which a plurality of kinds ofshapes of illumination areas illuminated by each element hologram areaare provided.

FIGS. 9A and 9B illuminate one illumination area with plural colors.

FIG. 10 is a view showing a schematic configuration of an illuminationdevice according to a third embodiment of the present invention.

FIG. 11 is a view showing an illumination area illuminated by theillumination device in FIG. 10.

FIG. 12 is a view showing an example of performing illumination so as toavoid an object.

FIG. 13 is a view showing a schematic configuration of an illuminationdevice according to a fourth embodiment of the present invention.

FIG. 14 is a view showing a schematic configuration of an illuminationdevice according to one embodiment of the present invention.

FIG. 15 is a view showing a light scanning device.

FIG. 16 is a view showing how a laser beam diffused by an optical deviceis incident on an illumination zone.

FIG. 17 is a view showing an example in which an illumination color of acentral portion in an illumination zone is different from anillumination color of the other portion of the illumination zone.

FIG. 18 is a view showing an example in which only the central portionin the illumination zone is made non-illuminated.

FIG. 19 is a view in which three hologram areas are adjacently arrangedalong an incident surface of a hologram recording medium.

FIG. 20 is a view in which three hologram areas are arranged in astacking direction.

FIG. 21 is a view showing an example in which the illumination deviceaccording to the present embodiment is applied to a headlight of a car.

FIGS. 22A to C are views showing a specific example of information in asecond area to be displayed using a headlight.

FIG. 23 is a view showing an example in which each element diffusionregion in the second diffusion region performs rectangular illuminationand the information on an arrow is displayed by combining theillumination areas of each element diffusion region.

FIG. 24 is a view showing a schematic configuration of an illuminationdevice according to a second embodiment of the present invention.

FIG. 25 is a view showing a schematic configuration of an illuminationdevice showing a first modification of FIG. 24.

FIG. 26 is a view showing a schematic configuration of an illuminationdevice showing a second modification of FIG. 24.

FIG. 27 is a view showing a schematic configuration of an illuminationdevice according to a seventh embodiment of the present invention.

FIG. 28 is a view showing a detailed configuration of an optical shutterand an optical device in the seventh embodiment.

FIGS. 29A and 29B are views schematically showing a structure of oneliquid crystal cell.

FIG. 30 is a view showing an example in which illumination andinformation display are performed in an illumination zone.

FIG. 31 is a view showing a schematic configuration of an illuminationdevice in which the arrangement of an optical shutter and an opticaldevice is reversed from that in FIG. 1.

FIG. 32 is a view showing a schematic configuration of an illuminationdevice according to an eighth embodiment of the present invention.

FIG. 33 is a view showing a detailed configuration of an optical shutterand an optical device in the eighth embodiment.

FIG. 34 is a view showing a schematic configuration of an illuminationdevice according to a ninth embodiment of the present invention.

FIG. 35 is a plan view of a diffusion unit in the illumination device ofFIG. 34.

FIG. 36A is a view showing how a first optical device reaches anillumination position of the coherent light beam.

FIG. 36B is a view showing how a second optical device reaches theillumination position of the coherent light beam.

FIG. 37 is a view showing a schematic configuration of an illuminationdevice according to a tenth embodiment of the present invention.

FIG. 38 is a view showing a schematic configuration of an illuminationdevice according to an eleventh embodiment of the present invention.

FIG. 39 is a view showing a schematic configuration of an illuminationdevice according to a twelfth embodiment of the present invention.

FIG. 40 is a plan view of a diffusion unit in the illumination device inFIG. 39.

FIG. 41 is a view showing a schematic configuration of an illuminationdevice according to a thirteenth embodiment of the present invention.

FIG. 42 is a plan view of a diffusion unit in the illumination device inFIG. 41.

FIG. 43 is a view showing a schematic configuration of an illuminationdevice according to a fourteenth embodiment of the present invention.

FIG. 44 is a view showing a schematic configuration of an illuminationdevice according to a fifteenth embodiment of the present invention.

FIG. 45 is a view showing a schematic configuration of an illuminationdevice according to a sixteenth embodiment of the present invention.

FIG. 46 is a view showing an example in which a region that meets a highbeam standard is illuminated in a predetermined area.

FIG. 47 is a view showing an example in which a region that meets a lowbeam standard is illuminated in a predetermined area.

FIG. 48 is a view showing a schematic configuration of an illuminationdevice according to a seventeenth embodiment of the present invention.

FIG. 49 is a view showing how the coherent light beam is scanned on theoptical device by the optical scanning unit.

FIG. 50 is a view showing how the coherent light beam is diffused by theoptical device enters a predetermined region.

FIG. 51 is a view showing how the coherent light beam is incident on anauxiliary optical device by an auxiliary mirror.

FIG. 52 is a view showing a schematic configuration of an illuminationdevice according to an eighteenth embodiment of the present invention.

FIG. 53 is a view showing how coherent light beam is incident on anoptical device by an auxiliary mirror.

FIG. 54 is a view showing a schematic configuration of an illuminationdevice according to a nineteenth embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention will be described below withreference to the drawings. In the drawings attached to the presentspecification, for ease of understanding and ease of understanding, thescales, the dimensional ratios in the length and breadth, and the likeare appropriately changed from those of the actual ones and exaggerated.

In addition, terms, geometric conditions and degrees thereof to be usedin the present specification, for example, terms such as “parallel”,“orthogonal”, “same” and the like, values of length, angle and the likeare strict shall be interpreted including a range that can expectsimilar functions without being bound by meaning.

First Embodiment

FIG. 1 is a view showing a schematic configuration of an illuminationdevice 1 according to the first embodiment of the present invention. Theillumination device 1 in FIG. 1 includes an irradiation device 2 and anoptical device 3. The irradiation device 2 includes a laser light source4 and a scanning unit 6.

The laser light source 4 emits coherent light beam, that is, laser beam.The laser light source 4 may be provided with a plurality of lightsource units with different emission wavelength ranges, but may beconfigured to have one or more light source units that emit laser beamin a single wavelength range. In this embodiment, an example in whichone or more light source units that emit laser beam in a singlewavelength range is provided will be described.

The scanning unit 6 scans a plurality of laser beams emitted by thelaser light source 4 on the optical device 3. The scanning unit 6 maymove the laser light source 4 to cause the respective laser beams toscan on the optical device 3, the optical device 3 may be moved so thateach laser beam is scanned on the optical device 3, and a light scanningdevice that changes a traveling direction of the laser beam from thelaser light source 4 may be provided so that each laser beam is scannedon the optical device 3. The technical features of the scanning unit 6are common to the following embodiments, but in each of the followingembodiments, the scanning unit 6 mainly includes a light scanningdevice, and the sign of the light scanning device is referred to as “6”.

The light scanning device 6 varies the traveling direction of the laserbeam from the laser light source 4 with the lapse of time so that thetraveling direction of the laser beam does not become constant. As aresult, the laser beam emitted from the light scanning device 6 isscanned on the incident surface of the optical device 3.

As shown in FIG. 2, for example, the light scanning device 6 has areflective device 13 that is rotatable around two rotating axes 11, 12extending in mutually intersecting directions. The laser beam from thelaser light source 4 incident on a reflecting surface 13 a of thereflective device 13 is reflected at an angle corresponding to aninclination angle of the reflecting surface 13 a and travels toward anincident surface 3 a of the optical device 3. By rotating the reflectivedevice 13 around the two rotation axes 11 and 12, the laser beam isscanned on the incident surface 3 a of the optical device 3two-dimensionally. Since the reflective device 13 repeats the operationof rotating around the two rotation axes 11 and 12 at a constant period,for example, the laser beam is repeatedly two-dimensionally scanned onthe incident surface 3 a of the optical device 3 in synchronization withthis period. In the case where the optical device 3 extends mainly in aone-dimensional direction, the optical device 3 may performone-dimensional scanning along the longitudinal direction of the opticaldevice 3.

The optical device 3 has the incident surface 3 a on which the laserbeam is incident, and diffuses the laser beam incident on the incidentsurface 3 a to illuminate a predetermined area. More specifically, thelaser beam diffused by the optical device 3 passes through anillumination zone 10 and then illuminates a predetermined area.

Here, the illumination zone 10 in FIG. 2 is an illumination zone of anear field illuminated by overlapping each diffusion region 14 in theoptical device 3. The illumination area of a far field is oftenexpressed as a diffusion angle distribution in an angular space ratherthan the dimension of the actual illumination zone. In the presentspecification, the term “illumination zone” includes a diffusion anglearea in the angular space in addition to the actual illumination zone(illumination area). Therefore, the predetermined area illuminated bythe illumination device in FIG. 1 can be a much wider area than theillumination zone 10 of the near field shown in FIG. 1. As will bedescribed later, the first area 15 and the second area 17 are includedin the predetermined area. The first area 15 and the second area 17 maybe arranged so as not to overlap with each other, or may be arranged sothat at least a part thereof overlaps. At least one of the first area 15and the second area 17 may be provided at a plurality of locations.

As shown in FIG. 2, the optical device 3 has a first diffusion region 16for illuminating the first area 15 and a second diffusion region 18 fordisplaying predetermined information in the second area 17. The firstarea 15 and the second area 17 are areas illuminated by the laser beampassing through the illumination zone 10 in FIG. 1, and are provided,for example, on the ground.

At least one of the first diffusion region 16 and the second diffusionregion 18 in the optical device 3 may be further divided into aplurality of element diffusion regions 19 finely. FIG. 2 shows anexample in which each of the first diffusion region 16 and the seconddiffusion region 18 is divided into the plurality of element diffusionregions 19, but this is merely an example. The simplest configuration isthe case where the optical device 3 has the first diffusion region 16including one element diffusion region 19 and the second diffusionregion 18 including another element diffusion region 19.

The laser beam from the light scanning device 6 is scanned on theoptical device 3. More specifically, the light scanning device 6sequentially scans each element diffusion region 19 in the firstdiffusion region 16 and the second diffusion region 18. Each elementdiffusion region 19 in the first diffusion region 16 illuminates apartial region in the first area 15. When the first diffusion region 16has only one element diffusion region 19, this element diffusion region19 illuminates the entire region of the first area 15. In some cases,each of the two or more element diffusion regions 19 included in thefirst diffusion region 16 may be illuminated while overlapping theentire region of the first area 15. On the other hand, each elementdiffusion region 19 in the second diffusion region 18 displaysinformation in the second area 17. When the second diffusion region 18has only one element diffusion region 19, this element diffusion region19 displays all the information of the second area 17. In the case wherethe plurality of element diffusion regions 19 are included in the seconddiffusion region 18, each element diffusion region 19 may share anddisplay one piece of information in the second area 17, and each elementdiffusion region 19 may display separate information in the second area17.

The illumination of the first area 15 may illuminate the entire regionin the first area 15 with a uniform illuminance or illumination may beperformed with nonuniform illuminance which varies depending on places.For example, the central portion of the first area 15 may be brightestand may be darker as it goes away from the center.

The information displayed in the second areas 17 is one in which atleast one of hue, brightness and saturation is changed in the secondarea 17. More specifically, the information displayed in the second area17 is, for example, at least one of a picture, a pattern, a letter, anumber and a symbol, and the specific content of the information is notparticularly limited. The information display in the second area 17 isperformed, for example, for the purpose of imparting design anddecorativeness, the purpose of calling attention, the purpose ofguidance display, the purpose of advertisement publicity, and the like.In addition, although the information displayed in the second area 17may be monochrome (monochrome) or multiple colors (color), in thepresent embodiment, an example of displaying information in a singlecolor will be described.

The optical device 3 is configured using, for example, the hologramrecording medium 30. As shown in FIG. 2, the hologram recording medium30 has a plurality of element hologram areas 31 corresponding to theplurality of element diffusion regions 19. In each element hologram area31, an interference fringe pattern is formed. When the laser beam fromthe light scanning device 6 is incident on the interference fringepattern, the laser beam is diffracted by the interference fringepattern, passes through the illumination zone 10, and illuminates thefirst area 15 and the second area 17.

In the element hologram area 31 in the first diffusion region 16, theinterference fringe pattern corresponding to the element hologram area31 is formed in advance so that the laser beam diffracted by the elementhologram area 31 illuminates the first area 15. In the element hologramarea 31 in the second diffusion region 18, the interference fringepattern corresponding to the element hologram area 31 is formed inadvance so that the laser beam diffracted by the element hologram area31 displays information in the second area 17.

By appropriately forming the appropriate interference fringe pattern ineach element hologram area 31 in the hologram recording medium 30 inthis manner, the illumination of the first area 15 and the informationdisplay of the second area 17 can be performed by the laser beamdiffracted at each element hologram area 31.

More specifically, the position, size and shape of the first area 15 canbe arbitrarily set by adjusting the interference fringe pattern formedin the element hologram area 31 for the first diffusion region 16.Similarly, by adjusting the interference fringe pattern formed in theelement hologram area 31 for the second diffusion region 18, theposition of the second area, and the type and size of the informationdisplayed in the second area 17 can be arbitrarily set.

The laser beam incident on each point in each element hologram area 31illuminates the corresponding first area 15 or second area 17. Further,the light scanning device 6 changes incident position and incident angleof the laser beam incident on the respective element hologram areas 31with the lapse of time. The laser beam incident into one elementhologram area 31 illuminates the common first area 15 or the second area17 even if the laser beam is incident on any position in the elementhologram area 31. That is, this means that the incident angle of thelaser beam incident on each point of a partial region 10 a changes withthe lapse of time. This change in the incident angle is a speed thatcannot be resolved by the human eye, and as a result, the scatteringpattern of the coherent light beam having no correlation is multiplexedand observed in the human eye. Therefore, the speckle generatedcorresponding to each scattering pattern is overlapped and averaged, andis observed by the observer. As a result, in the illumination zone 10,speckle becomes less conspicuous. In addition, since the laser beam fromthe light scanning device 6 sequentially scans each of the elementhologram areas 31 on the hologram recording medium 16, the laser beamsdiffracted at each point in each element hologram area 31 have differentwave fronts; therefore, since these laser beams are individuallysuperimposed on the illumination zone 10, a uniform illuminancedistribution in which the speckle is inconspicuous can be obtained inthe illumination zone 10.

In FIG. 2, the shape of the element hologram area 31 is rectangular, butthe shape of the element hologram area 31 is arbitrary. The shapes andsizes of the first area 15 and the second area 17 illuminated by thelaser beam diffused in the element hologram area 31 depend on the typeof the interference fringe pattern formed in the element hologram area31 and do not depend on the shape and size of the element hologram area31. Therefore, the shape and size of the element hologram area 31 may bearbitrary. However, it is necessary for the element hologram area 31 tohave a size and shape capable of scanning laser beam.

Also, the arrangement direction of the element hologram areas 31 is alsoarbitrary. For example, FIG. 3A shows an example of the hologramrecording medium 30 in which a plurality of element hologram areas 31are arranged adjacent to each other in the vertical direction. Inaddition, FIG. 3B show an example in which the hologram recording medium30 is configured by an element hologram area group 30 a in which thetriangular element hologram areas 31 are arranged without gaps and anelement hologram area group 30 b in which the plurality of elementhologram areas 31 are arranged adjacently in the horizontal direction.In FIG. 3B, for example, one of the two element hologram area groups 30a and 30 b corresponds to the first diffusion region 16 and the othercorresponds to the second diffusion region 18.

The illumination of the first area 15 and the information display of thesecond area 17 can be performed on either hologram recording medium 30in FIG. 3A or FIG. 3B. That is, the arrangement and shape of eachelement hologram area 31 in the hologram recording medium 30 arearbitrary, and by adjusting the interference fringe pattern formed ineach element hologram area 31, the illumination of the first area 15 andthe information display of the second area 17 can be performed.

FIG. 2 shows an example in which the first area 15 and the second area17 are provided at different locations, but the second area 17 may beprovided in the first area 15 as shown in FIG. 4. In the case of FIG. 4,the information of the second area 17 is displayed inside theillumination area in the first area 15. As described above, where to setthe first area 15 and the second area 17 can be arbitrarily adjusteddepending on the type of the interference fringe pattern formed in eachelement hologram area 31.

FIG. 4 shows an example in which each element hologram area 31 in thefirst diffusion region 16 illuminates a partial region (a rectanglesurrounded by a broken line in FIG. 4) in the first area 15, and theaggregate of these partial regions illuminates the first area 15. Thisis only an example, and as described above, each element hologram area31 may illuminate the entire region of the first area 15 in anoverlapping manner, and a part of the element hologram area 31 mayilluminate different partial regions and the remaining element hologramarea 31 may illuminate the same partial region in an overlapped manner.When a plurality of element hologram areas 31 illuminate a common areain an overlapping manner, the illumination illuminance of that areaincreases; therefore, an area to be illuminated while being overlappedand area to be illuminated while not being overlapped are mixed, so thata pattern and picture can be displayed.

Each of the element hologram areas 31 for the first diffusion region 16can be produced by using, for example, scattered light from a realscattering plate as object light. More specifically, when the hologramphotosensitive material which is the base of the hologram recordingmedium 30 is illuminated with reference light and object light made ofcoherent light beam having coherency with each other, an interferencefringe pattern due to interference of these light beams is formed on thehologram photosensitive material, and the hologram recording medium 30is manufactured. A laser beam which is coherent light beam is used asthe reference light, and scattered light of an isotropic scatteringplate which is available at low cost, for example, is used as the objectlight.

By illuminating the hologram recording medium 30 with a laser beam fromthe focal position of the reference light used for manufacturing thehologram recording medium 30, a reproduced image of the scattering plateis generated at the arrangement position of the scattering plate whichis the source of the object light used in manufacturing the hologramrecording medium 30. When the scattering plate which is the source ofthe object light used for manufacturing the hologram recording medium 30has uniform surface scattering, a reproduced image of the scatteringplate obtained by the hologram recording medium 30 is also a uniformplane illumination, and a region where the reproduced image of thisscattering plate is generated is the illumination zone 10.

In each element hologram area 31 for the second diffusion region 18,which displays information in the second area 17 in the hologramrecording medium 30, it is possible to form an interference fringepattern by the same procedure as described above by using the scatteringplate on which an information image is formed in advance.

In the hologram recording medium 30 according to the present embodiment,it is necessary to perform illumination in the first area 15 andinformation display in the second area 17, so that the interferencefringe pattern becomes complicated. Without using actual object lightand reference light, such a complicated interference fringe pattern canbe designed using a computer based on the scheduled wavelength andincident direction of the reconstruction illumination light and theshape and position of the image to be reproduced. The hologram recordingmedium 30 thus obtained is also called a computer generated hologram(CGH). In addition, a Fourier transform hologram having the samediffusion angle characteristic at each point on each element hologramarea 31 may be formed by computer synthesis. Furthermore, an opticalmember such as a lens may be provided on the rear side of the opticalaxis of the illumination zone 10 to set the size and position of theactual illumination area.

One advantage of providing the hologram recording medium 30 as theoptical device 3 is that the optical energy density of the laser beamcan be reduced by diffusion, and in addition, another advantage is thatsince the hologram recording medium 30 can be used as a directivitysurface light source, the luminance on the light source surface forachieving the same illuminance distribution can be reduced compared withthe conventional lamp light source (point light source). This cancontribute to improving the safety of the laser beam, and even if thelaser beam having passed through the illumination zone 10 is vieweddirectly with a human eye, there is less possibility of adverselyaffecting the human eye as compared with the case of looking directly ata single point light source.

FIG. 1 shows an example in which the laser beam from the light scanningdevice 6 diffuses through the optical device 3, but the optical device 3may diffuse and reflect the laser beam. For example, when the hologramrecording medium 30 is used as the optical device 3, the hologramrecording medium 30 may be a reflection type or a transmission type.Generally, the reflection type hologram recording medium 30(hereinafter, reflection type holo) has high wavelength selectivity ascompared with the transmission type hologram recording medium 30(hereinafter, transmission type holo). That is, even when theinterference fringe pattern corresponding to different wavelengths islaminated the reflection type holo can diffract coherent light beam of adesired wavelength only in a desired layer. Also, the reflection typeholo is superior in that it is easy to remove the influence of zeroorder light. On the other hand, the transmission type holo has a widediffractable spectrum and a wide tolerance of the laser light source 4;however, when the interference fringe pattern corresponding to differentwavelengths is laminated, coherent light beam of a desired wavelength isdiffracted even in a layer other than the desired layer. Therefore, ingeneral, it is difficult to form a transmission type holo with alaminated structure.

As a specific form of the hologram recording medium 30, a volumehologram recording medium 30 using a photopolymer may be used, avolumetric hologram recording medium 30 of a type that performsrecording using a photosensitive medium containing a silver saltmaterial may be used, and a relief type (emboss type) hologram recordingmedium 30 may be used.

The specific form of the optical device 3 is not limited to the hologramrecording medium 30, and may be various diffusion members that can befinely divided into the plurality of element diffusion regions 19. Forexample, the optical device 3 may be configured using a lens array groupin which each element diffusion region 19 is a single lens array. Inthis case, a lens array is provided for each element diffusion region19, and the shape of each lens array is designed so that each lens arrayilluminates the partial region 10 a in the illumination zone 10. Atleast a part of the position of each partial region 10 a is different.As a result, as in the case of configuring the optical device 3 usingthe hologram recording medium 30, it is possible to perform theillumination of the first area 15 and the information display of thesecond area 17.

For example, when the information on the arrow is displayed using thelens array as each element diffusion region 19 for the second diffusionregion 18, the outer shape of the lens array may be an arrow shape. Inthis manner, by machining the outer shape of the lens array to anarbitrary shape, an orientation distribution for arbitrary informationcan be formed by each lens array.

Furthermore, the optical device 3 may be formed by combining thehologram recording medium 30 and the lens array. That is, one of thefirst diffusion region 16 and the second diffusion region 18 may beconfigured by the hologram recording medium 30, and the other may beformed of a lens array group.

As described above, in the first embodiment, since the illumination ofthe first area 15 and the information display of the second area 17 areperformed using the coherent light beam, it is possible to displaydesired information at an arbitrary location while illuminating aportion requiring illumination. Therefore, in addition to the originallighting function, it is possible to provide the illumination device 1taking into consideration the functions such as the designability,decorativeness, practicality and the like by information display.

Further, the light scanning device 6 scans laser beam in each elementdiffusion region 19, and the laser beam incident on each point in eachelement diffusion region 19 illuminates a part or the entire region ofthe corresponding first area 15 or second area 17; therefore, theincident angle of the laser beam in the first area 15 or the second area17 changes with the lapse of time, so that a speckle in the first area15 or the second area 17 is less noticeable.

Second Embodiment

In the second embodiment described below, the timing of the laser beamfrom the laser light source 4 is controlled.

FIG. 5 is a view showing a schematic configuration of the illuminationdevice 1 according to a second embodiment of the present invention. Theillumination device 1 of FIG. 5 is different from FIG. 1 in that thetiming control unit 5 is provided inside the irradiation device 2.Further, the laser light source 4 in FIG. 5 has the plurality of lightsource units 7 that emit the plurality of coherent light beams, i.e.,laser beams having different emission wavelength ranges. The pluralityof light source units 7 may be provided individually or may be a lightsource module in which the plurality of light source units 7 arearranged side by side on a common substrate. It is sufficient that thelaser light source 4 of the present embodiment has at least two lightsource units 7 having different emission wavelength ranges, and thenumber of types of emission wavelength ranges may be two or more. Inorder to increase the emission intensity, the plurality of light sourceunits 7 may be provided for each emission wavelength range.

For example, in the case where the laser light source 4 has a lightsource unit 7 r in a red emission wavelength range, a light source unit7 g in a green emission wavelength range, and a light source unit 7 b ina blue emission wavelength range, white illumination light can begenerated by overlapping the three laser beams emitted from the lightsource units 7.

In the second embodiment, it is not indispensable to provide theplurality of light source units 7 having different emission wavelengthranges, and as in the first embodiment, one or more light source units 7emitting laser beam in a single wavelength range may be provided.Hereinafter, an example in which the plurality of light source units 7having different emission wavelength ranges are provided will bedescribed.

The timing control unit 5 individually controls the incident timing ofthe plurality of coherent light beams to the optical device 3 or theillumination timing of the illumination zone (illumination area) 10. Thetiming control unit 5 may control the light emission timing from thelaser light source 4, the incident timing of the laser beam incident onthe optical device 3 may be controlled, or the illumination timing atwhich the laser beam diffused by the optical device 3 illuminates theillumination area may be controlled. The timing control unit 5synchronizes the scanning timing of the laser beam (coherent light beam)by the light scanning device 6 so that the illumination mode of theillumination zone (illumination area) 10 periodically or temporarilychanges, and controls the light emission timing of each laser beam, theincident timing to the optical device 3, or the illumination timing ofthe illumination area. Although the above-described technical featuresof the timing control unit 5 are common in each of the followingembodiments, in each of the following embodiments, an example in whichthe timing control unit 5 controls the light emission timing from thelaser light source 4 is mainly described.

The timing control unit 5 controls whether or not to scan the coherentlight beam from the light scanning device 6 with at least one of thefirst diffusion region 16 and the second diffusion region 18. Forexample, the timing control unit 5 may continuously scan the firstdiffusion region 16 and switch whether or not to scan at least a part ofthe second diffusion region 18. As a result, the first area 15 isconstantly illuminated, and the second area 17 can display informationonly when necessary. Alternatively, conversely, the timing control unit5 may switch whether or not to scan at least a part of the firstdiffusion region 16, and may continuously scan the second diffusionregion 18.

The timing control unit 5 individually controls the timing of theplurality of laser beams having different emission wavelength ranges.That is, when the plurality of light source units 7 are providedcorresponding to a plurality of laser beams having different emissionwavelength ranges, the timing control unit 5 controls the timing atwhich the laser beams are individually emitted from the plurality oflight source units 7. As described above, when the laser light source 4is capable of emitting three laser beams of red, blue, and green, bycontrolling the timing of each laser beam, it is possible to generateillumination light of a color in which arbitrary one or more colors ofred, blue and green are mixed.

The timing control unit 5 may control whether or not to emit laser beamfrom each light source unit 7, that is, on/off of light emission, andmay switch whether or not to guide the laser beam emitted from eachlight source unit 7 to the incident surface of the light scanning device6. In the latter case, an optical shutter unit (not shown) is providedbetween each light source unit 7 and the light scanning device 6, andthe passing/blocking of laser beam is switched by the optical shutterunit.

FIG. 6 is a view showing how the laser beam diffused by the opticaldevice 3 is incident on the illumination zone 10. The optical device 3has a plurality of diffusion region parts 14 corresponding to theplurality of laser beams. Corresponding laser beam is incident on eachdiffusion region part 14. Each of the diffusion region parts 14 includesthe first diffusion region 16 and the second diffusion region 18 as inthe first embodiment. The arrangement order of the first diffusionregion 16 and the second diffusion region 18 in each diffusion regionpart 14 is arbitrary and the ratio between the first diffusion region 16and the second diffusion region 18 in each diffusion region part 14 isalso arbitrary.

Each diffusion region part 14 diffuses the incident laser beam andilluminates the entire region of the illumination zone 10. Eachdiffusion region part 14 has the plurality of element diffusion regions19. Each element diffusion region 19 diffuses the incident laser beamand illuminates a partial region in the illumination zone 10. At least apart of the partial region differs for each element diffusion region 19.

The optical device 3 is configured using, for example, the hologramrecording medium 30. The hologram recording medium 30 has, for example,as shown in FIG. 6, a plurality of hologram areas 32. Each of thehologram areas 32 is provided corresponding to each of the plurality oflaser beams having different emission wavelength ranges. The laser beamsincident on the incident surface of each hologram area 32 are diffusedto illuminate the illumination zone 10. For example, when the hologramrecording medium 30 has three hologram areas 32, the laser beam diffusedin each hologram area 32 illuminates the entire region of theillumination zone 10.

FIG. 6 shows an example in which three hologram areas 32 correspondingto three diffusion region parts 14 are provided in association withthree laser beams that emit light in red, blue, or green. However, thehologram recording medium 30 according to the present embodiment mayhave two or more hologram areas 32 in association with two or more laserbeams having different emission wavelength ranges. As shown in FIG. 6,when the hologram recording medium 30 has three hologram areas 32corresponding to three laser beams that emit light in red, blue, orgreen, each hologram area 32 illuminates the entire region of theillumination zone 10, so that when the three laser beams emit light, theillumination zone 10 is illuminated with white light.

The size, that is, the area of each hologram area 32 in the hologramrecording medium 30 is not necessarily the same. Even if the sizes ofthe respective hologram areas 32 are different, by individuallyadjusting the interference fringe pattern formed on the incident surface17 a of each hologram area 32, each hologram area 32 can illuminate thecommon illumination zone 10.

Each of the plurality of hologram areas 32 has the plurality of elementhologram areas 31. Each element hologram area 31 is the first diffusionregion 16 or the second diffusion region 18. Each element hologram area31 illuminates the partial region 10 a in the illumination zone 10 bydiffusing the incident laser beam. At least a part of the partial regionilluminated by each element hologram area 31 is different for eachelement hologram area 31. That is, the partial regions 10 a illuminatedby the different element hologram areas 31 are at least partiallydifferent from each other.

The partial region illuminated by the element hologram area 31corresponding to the first diffusion region 16 illuminates the firstarea 15 after passing through the illumination zone 10. The partialregion illuminated by the element hologram area 31 corresponding to thesecond diffusion region 18 displays information in the second area 17after passing through the illumination zone 10.

Since the illumination device 1 according to the present embodiment hasthe timing control unit 5, at least one of the illumination of the firstarea 15 and the information display of the second area 17 can beperformed at an arbitrary timing. In addition, by controlling thescanning timing of the laser beam in an arbitrary hologram area out ofthe hologram areas provided for each color, it is possible to change theillumination color of part of the illumination area illuminated by thelaser beam passing through the illumination zone 10 or to performillumination control so as not to illuminate only a part of theillumination area as needed.

In the above example, the timing of at least one of the illumination ofthe first area 15 and the information of the second area 17 is switchedor the illumination color is changed by the timing; however, anothermethod for changing the illumination mode of a part of the illuminationzone 10 is conceivable. For example, when the laser light source 4 has aplurality of light source units 7 that emit light in the same emissionwavelength range, the light emission of a part of the light source units7 may be stopped so that the illumination intensity of a part of theinside of the illumination zone 10 is lower than the illuminationintensity of the surrounding area. Conversely, a part of theillumination intensity in the illumination zone 10 may be higher thanthe surrounding illumination intensity. In addition, a part of theinside of the illumination zone 10 may be illuminated with flashing.Alternatively, a part of the color in the illumination zone 10 may bechanged continuously or intermittently.

At least a part of the illumination area illuminated by the elementhologram areas 31 corresponding to the first diffusion region 16 in thefirst area 15 may be overlapped. FIG. 7 shows an example in which partsof rectangular illumination areas in the first area 15 overlap with eachother. When a part of each illumination area illuminated by each elementhologram area 31 overlaps, the illuminance of the overlapped part ishigher; therefore, even if the illumination color is the same, itbecomes more conspicuous. By designing the shapes and sizes ofoverlapping parts, it is also possible to impart aesthetic design.

Furthermore, the shape of the illumination area illuminated by eachelement hologram area 31 is arbitrary. FIG. 8 is a view showing anexample in which a plurality of kinds of shapes of illumination areasilluminated by each element hologram area 31 are provided. By combininga plurality of illumination areas such as a polygon, a circle, a star,and the like, it is possible to have designability and decorativeness.Further, as shown in FIG. 8, by overlapping some illumination areas withFIG. 7, a part of the illumination area can be made conspicuous. Itshould be noted that FIG. 8 is applicable to any of the illuminationshapes of the first area 15 and the second area 17.

Further, as shown in FIG. 9, by displaying one illumination area with aplurality of colors, more design and decorativeness can be provided.FIG. 9A shows an example in which the illumination of the first area 15is performed with a plurality of colors, and FIG. 9B shows an example inwhich the information display of the second area 17 is performed with aplurality of colors.

In this way, in the second embodiment, the timing control unit 5 canarbitrarily control the timing of the laser beam scanning the opticaldevice 3. Therefore, at least one of the illumination of the first area15 and the information display of the second area 17 can be performed atan arbitrary timing. It is also possible to switch at least one of theillumination mode of the first area 15 and the illumination mode of theinformation display of the second area 17 at an arbitrary timing.

Third Embodiment

The third embodiment described below changes the illumination mode ofthe object existing in the illumination zone 10.

FIG. 10 is a view showing a schematic configuration of the illuminationdevice 1 according to a third embodiment of the present invention, FIG.11 and FIG. 12 are views showing the illumination area illuminated bythe illumination device 1 in FIG. 10. The illumination device 1 in FIG.10 includes an object detection unit 21 in addition to the configurationof the illumination device 1 in FIG. 1. The object detection unit 21detects an object 22 existing in a predetermined area 23 illuminable bythe optical device 3. That is, the object detection unit 21 detects theobject 22 existing in the illumination area 23 that can be illuminatedby the laser beam passing through the illumination zone 10 in FIG. 10.The object 22 is a human being, a vehicle, an organism, and the like,and the object may be a moving body or a stationary body.

The object detection unit 21 may be a sensor that optically detects theobject 22. For example, an infrared ray is applied from the sensor tothe illumination zone 10, and the presence or absence of the object 22and the position and size of the object 22 may be detected depending onwhether or not the reflected light is detected in a predetermined timeby the sensor. Alternatively, the image of the illumination zone 10 maybe captured by a camera, and the captured image may be analyzed by imagerecognition such as pattern matching to detect the presence or absenceof the object 22 and the position and size of the object 22.

When the object detection unit 21 detects the object 22, the timingcontrol unit 5 controls the timing of the plurality of light sourceunits 7 according to the position and the size of the object 22. Morespecifically, the timing control unit 5 controls the scanning timing ofthe laser beam in the first diffusion region 16 so as to illuminate onlythe periphery of the object 22.

FIG. 11 shows an example in which the position of the first area 15 ismoved in accordance with the movement of the object 22 so that theperiphery of the object 22 is illuminated. The arrow line in FIG. 11indicates the movement path of the object 22.

Thus, according to the third embodiment, it is possible to illuminatethe periphery of the object 22 while constantly tracking the object 22.FIG. 11 shows an example in which the object 22 is always illuminatedwith the same color, but the object 22 may be illuminated with differentcolors according to the position of the object 22. Changing theillumination color can be also realized by the timing control unit 5controlling the timing of the plurality of light source units 7individually.

FIG. 12 shows an example of illuminating so as to avoid the object 22,contrary to FIG. 11. For example, FIG. 12 can be used to grasp themovement path of the object 22 by illuminating the path through whichthe object 22 has passed. Also in the case of FIG. 12, in accordancewith the position of the object 22 detected by the object detection unit21, by controlling the scanning timing of the laser beam scanning thefirst diffusion region 16 by the timing control unit 5, it is possibleto perform illumination so as to avoid the object 22 by moving the firstarea 15 in accordance with the movement of the object 22. Also in FIG.12, illumination with different colors may be performed depending on theposition of the object 22.

The method of changing the illumination mode according to the positionof the object 22 detected by the object detection unit 21 is not limitedto the example shown in FIG. 11 and FIG. 12. For example, a direction inwhich the object 22 moves may be predicted, and an area where the object22 may move may be illuminated. In addition, information on the secondarea 17 may be displayed at and around the position of the object 22.

As described above, in the third embodiment, since the illumination ofthe first area 15 or the information display of the second area 17 isperformed in accordance with the movement of the object 22, it becomeseasy to grasp the moving position of the object 22, and it is alsopossible to continuously provide desired information to the movingobject 22.

Fourth Embodiment

In the fourth embodiment described below, at least one of theillumination of the first area 15 and the information display of thesecond area 17 is performed when an event occurs.

FIG. 13 is a view showing a schematic configuration of the illuminationdevice 1 according to a fourth embodiment of the present invention. Theillumination device 1 in FIG. 13 is provided with an event detectionunit 24 in the illumination device 1 in FIG. 5. The event detection unit24 detects occurrence of a specific event. Here, the specific event is,for example, in the case of the illumination device 1 for a vehicle, acase where the vehicle engine is turned on or off, a case where the dooris opened and closed, and the like. When such a specific event occurs,the timing control unit 5 controls the timing of the plurality of lightemitting units 7.

Thus, in the case where the illumination device 1 is a vehicleheadlight, for example, while the vehicle is moving, the first area 15is illuminated and the illumination device 1 is used for normal lightingpurposes, and when the vehicle is stopped, the information of the secondarea 17 can be displayed with the headlight. Although the information tobe displayed is arbitrary, for example, if a brand name, manufacturername, vehicle type name etc. of the vehicle is displayed as information,it also becomes a publicity of the vehicle, thereby giving superiorityto the owner of the vehicle.

In addition to the headlight, if the illumination device 1 is providedaround the door of the vehicle, when an event that the door is openedoccurs, illumination and information display that catches passenger'seyes can be performed near a place where a passenger gets off thevehicle, thereby creating a high-class feeling of the vehicle.

As described above, in the fourth embodiment, when an event occurs, inorder to perform at least one of the illumination of the first area 15and the information display of the second area 17 or to switch theillumination and information display, illumination can be performed forthe purposes of advertisement promotion, attention calling, designimprovement, and the like. It should be noted that both the objectdetection unit 21 and the above-described event detection unit 24 in thethird embodiment may be provided.

The vehicle equipped with the illumination device 1 according to thefirst to fourth embodiments is not necessarily limited to a car, and maybe various moving bodies such as aircraft and other flying objects,trains, or ships. In addition, the illumination device 1 is not limitedto being mounted on a vehicle, and may be installed at an arbitraryplace.

Fifth Embodiment

FIG. 14 is a view showing a schematic configuration of the illuminationdevice 1 according to the fifth embodiment of the present invention. Theillumination device 1 in FIG. 14 includes the irradiation device 2 andthe optical device 3. The irradiation device 2 includes the laser lightsource 4, the timing control unit 5, and the light scanning device 6.

The laser light source 4 has the light source unit 7 that emits coherentlight beam of a predetermined emission wavelength range, that is, alaser beam. When illuminating with two or more colors, it is necessaryto provide the laser light source 4 with the plurality of light sourceunits 7 that emit a plurality of laser beams having different emissionwavelength ranges. The plurality of light source units 7 may be providedindividually or may be a light source module in which the plurality oflight source units 7 are arranged side by side on a common substrate.However, the laser light source 4 of the present embodiment may have atleast one light source unit 7. Further, in order to increase the lightemission intensity, the plurality of light source units 7 that emitlaser beam of a common emission wavelength range may be provided.

In the present embodiment, an example will be described in which thelaser light source 4 has the light source unit 7 r in the red emissionwavelength range, the light source unit 7 g in the green emissionwavelength region, and the light source unit 7 b in the blue emissionwavelength range. By overlapping the three laser beams emitted from thelight source units 7, white illumination light can be generated.

The timing control unit 5 individually controls the timing of theplurality of laser beams having different emission wavelength ranges.That is, when the plurality of light source units 7 are providedcorresponding to a plurality of laser beams having different emissionwavelength ranges, the timing control unit 5 individually controls thetiming at which the laser beams are emitted from the plurality of lightsource units 7. As described above, when the laser light source 4 iscapable of emitting three laser beams of red, blue, and green, bycontrolling the timing of each laser beam, it is possible to generateillumination light of a color in which arbitrary one or more colors ofred, blue and green are mixed.

The timing control unit 5 may control whether or not to emit laser beamfrom each light source unit 7, that is, on/off of light emission, andmay switch whether or not to guide the laser beam emitted from eachlight source unit 7 to the incident surface of the light scanning device6. In the latter case, an optical shutter unit (not shown) is providedbetween each light source unit 7 and the light scanning device 6, andthe passing/blocking of laser beam is switched by the optical shutterunit.

The light scanning device 6 varies the traveling direction of the laserbeam from the laser light source 4 with the lapse of time so that thetraveling direction of the laser beam does not become constant. As aresult, the laser beam emitted from the light scanning device 6 isscanned on the incident surface of the optical device 3.

As shown in FIG. 15, for example, the light scanning device 6 has thereflective device 13 that is rotatable around two rotating axes 11, 12extending in mutually intersecting directions. The laser beam from thelaser light source 4 incident on the reflecting surface 13 a of thereflective device 13 is reflected at an angle corresponding to aninclination angle of the reflecting surface 13 a and travels toward anincident surface 3 a of the optical device 3. By rotating the reflectivedevice 13 around the two rotation axes 11 and 12, the laser beam isscanned on the incident surface of the optical device 3two-dimensionally. Since the reflective device 13 repeats the operationof rotating around the two rotation axes 11 and 12 at a constant period,for example, the laser beam is repeatedly two-dimensionally scanned onthe incident surface 3 a of the optical device 3 in synchronization withthis period.

In the present embodiment, it is assumed that only one light scanningdevice 6 is provided, all of the plurality of laser beams emitted fromthe laser light source 4 are incident on the common light scanningdevice 6, the traveling direction of the light scanning device 6 ischanged with the lapse of time, and the optical device 3 is scanned.

The optical device 3 has the incident surface 3 a on which the pluralityof laser beams are incident, and diffuses the plurality of laser beamsincident on the incident surface 3 a to illuminate a predetermined area.More specifically, the plurality of laser beams diffused by the opticaldevice 3 passes through the illumination zone 10 and then illuminates apredetermined area that is an actual illumination area 20.

Here, the illumination zone 10 is an illumination zone of a near fieldilluminated by overlapping each diffusion region 14 in the opticaldevice 3. The illumination area of a far field is often expressed as adiffusion angle distribution in an angular space rather than thedimension of the actual illumination zone. In the present specification,the term “illumination zone” includes a diffusion angle area in theangular space in addition to the actual illumination zone (illuminationarea). Therefore, the predetermined area illuminated by the illuminationdevice in FIG. 1 can be a much wider area than the illumination zone 10of the near field shown in FIG. 1.

As shown in FIG. 15, the optical device 3 has the first diffusion region16 for illuminating the first area 15 and the second diffusion region 18for displaying predetermined information in the second area 17. Thefirst area 15 and the second area 17 are areas illuminated by the laserbeam passing through the illumination zone 10 in FIG. 1, and areprovided, for example, on the ground.

At least one of the first diffusion region 16 and the second diffusionregion 18 in the optical device 3 may be further divided into theplurality of element diffusion regions 19 finely. FIG. 15 shows anexample in which each of the first diffusion region 16 and the seconddiffusion region 18 is divided into the plurality of element diffusionregions 19, but this is merely an example. The simplest configuration isthe case where the optical device 3 has the first diffusion region 16including one element diffusion region 19 and the second diffusionregion 18 including another element diffusion region 19.

The laser beam from the light scanning device 6 is scanned on theoptical device 3. More specifically, the light scanning device 6sequentially scans each element diffusion region 19 in the firstdiffusion region 16 and the second diffusion region 18. Each elementdiffusion region 19 in the first diffusion region 16 illuminates apartial region in the first area 15. When the first diffusion region 16has only one element diffusion region 19, this element diffusion region19 illuminates the entire region of the first area 15. In some cases,each of the two or more element diffusion regions 19 included in thefirst diffusion region 16 may be illuminated while overlapping theentire region of the first area 15. On the other hand, each elementdiffusion region 19 in the second diffusion region 18 displaysinformation in the second area 17. When the second diffusion region 18has only one element diffusion region 19, this element diffusion region19 displays all the information of the second area 17. In the case wherethe plurality of element diffusion regions 19 are included in the seconddiffusion region 18, each element diffusion region 19 may share anddisplay one piece of information in the second area 17, and each elementdiffusion region 19 may display separate information in the second area17.

The illumination of the first area 15 may illuminate the entire regionin the first area 15 with a uniform illuminance or illumination may beperformed with nonuniform illuminance which varies depending on places.For example, the central portion of the first area 15 may be brightestand may be darker as it goes away from the center.

The information displayed in the second areas 17 is one in which atleast one of hue, brightness and saturation is changed in the secondarea 17. More specifically, the information displayed in the second area17 is, for example, at least one of a picture, a pattern, a letter, anumber and a symbol, and the specific content of the information is notparticularly limited. The information display in the second area 17 isperformed, for example, for the purpose of imparting design anddecorativeness, the purpose of calling attention, the purpose ofguidance display, the purpose of advertisement publicity, and the like.In addition, although the information displayed in the second area 17may be monochrome (monochrome) or multiple colors (color), in thepresent embodiment, an example of displaying information in a singlecolor will be described.

FIG. 16 is a view showing how the laser beam diffused by the opticaldevice 3 is incident on the illumination zone 10. The optical device 3has a plurality of diffusion region parts 14 corresponding to theplurality of laser beams. Corresponding laser beam is incident on eachdiffusion region part 14. Each of the diffusion region parts 14 includesthe first diffusion region 16 and the second diffusion region 18 as inthe fifth embodiment. The arrangement order of the first diffusionregion 16 and the second diffusion region 18 in each diffusion regionpart 14 is arbitrary and the ratio between the first diffusion region 16and the second diffusion region 18 in each diffusion region part 14 isalso arbitrary.

Each diffusion region part 14 diffuses the incident laser beam andilluminates the entire region of the illumination zone 10. Eachdiffusion region part 14 has the plurality of element diffusion regions19. Each element diffusion region 19 diffuses the incident laser beamand illuminates a partial region 10 b in the illumination zone 10. Atleast a part of the partial region 10 b differs for each elementdiffusion region 19.

The optical device 3 is configured using, for example, the hologramrecording medium 30. The hologram recording medium 30 has, for example,as shown in FIG. 16, a plurality of hologram areas 32. Each of thehologram areas 32 is provided corresponding to each of the plurality oflaser beams having different emission wavelength ranges. The laser beamsincident on the incident surface of each hologram area 32 are diffusedto illuminate the illumination zone 10. For example, when the hologramrecording medium 30 has three hologram areas 32, the laser beam diffusedin each hologram area 32 illuminates the entire region of theillumination zone 10.

FIG. 16 shows an example in which three hologram areas 32 are providedin association with three laser beams that emit light in red, blue, orgreen. However, since the hologram recording medium 30 may be used formonochromatic illumination, the hologram recording medium 30 may beprovided with one or more hologram areas 32. As shown in FIG. 16, whenthe hologram recording medium 30 has three kinds of hologram areas 32corresponding to three kinds of laser beams that emit light in red,blue, or green, each hologram area 32 illuminates the entire region ofthe illumination zone 10, so that when the three laser beams emit light,the illumination zone 10 is illuminated with white light.

The size, that is, the area of each hologram area 32 in the hologramrecording medium 30 is not necessarily the same. Even if the sizes ofthe respective hologram areas 32 are different, by individuallyadjusting the interference fringe pattern formed on the incident surface17 a of each hologram area 32, each hologram area 32 can illuminate thecommon illumination zone 10.

Each of the plurality of hologram areas 32 has the plurality of elementhologram areas 31. Each of the plurality of element hologram areas 31illuminates the partial region 10 b in the illumination zone 10 bydiffusing the incident laser beam. At least a part of the partial region10 b illuminated by each element hologram area 31 is different for eachelement hologram area 31. That is, the partial regions 10 b illuminatedby the different element hologram areas 31 are at least partiallydifferent from each other.

An interference fringe pattern is formed on an incident surface 17 a ofeach element hologram area 31. Therefore, the laser beam incident on theincident surface 17 a of each element hologram area 31 is diffracted bythe interference fringe pattern on the incident surface 17 a, andilluminates the corresponding partial region 10 b on the illuminationzone 10. By adjusting the interference fringe pattern variously, it ispossible to change the traveling direction of the laser beam diffractedor diffused in each element hologram area 31.

In this manner, the laser beams incident on each point in each elementhologram area 31 illuminate the corresponding partial region 10 b.Further, the light scanning device 6 changes incident position andincident angle of the laser beam incident on the respective elementhologram areas 31 with the lapse of time. The laser beam incident intoone element hologram area 31 illuminates the common partial region 10 beven if the laser beam is incident on any position in the elementhologram area 31. That is, this means that the incident angle of thelaser beam incident on each point of a partial region 10 b changes withthe lapse of time. This change in the incident angle is a speed thatcannot be resolved by the human eye, and as a result, the scatteringpattern of the coherent light beam having no correlation is multiplexedand observed in the human eye. Therefore, the speckle generatedcorresponding to each scattering pattern is overlapped and averaged, andis observed by the observer. As a result, in the illumination zone 10,speckle becomes less conspicuous. In addition, since the laser beam fromthe light scanning device 6 sequentially scans each of the elementhologram areas 31 on the hologram recording medium 30, the laser beamsdiffracted at each point in each element hologram area 31 have differentwave fronts; therefore, since these laser beams are individuallysuperimposed on the illumination zone 10, a uniform illuminancedistribution in which the speckle is inconspicuous can be obtained inthe illumination zone 10.

FIG. 16 shows an example in which each element hologram area 31illuminates different partial regions 10 b in the illumination zone 10.However, a part of the partial region 10 b may overlap the adjacentpartial region 10 b. In addition, the size of the partial region 10 bmay be different for each elementary hologram area 31. Furthermore, itis unnecessary that the corresponding partial region 10 b is arranged inthe illumination zone 10 according to the arrangement order of theelement hologram area 31. That is, the arrangement order of the elementhologram area 31 in the hologram area 32 and the arrangement order ofthe corresponding partial region 10 b in the illumination zone 10 arenot necessarily coincident.

In the illumination device 1 according to the present embodiment,desired information can be displayed in the second area 17 as necessarywhile illuminating the first area 15 with the laser beam passing throughthe illumination zone 10.

FIGS. 17 and 18 show an example in which the illumination mode of thecentral portion 10 a in the illumination zone 10 is different from theillumination mode of the other portion in the illumination zone 10. Inthis case, even also in the illumination area illuminated by the laserbeam passing through the illumination zone 10, the illumination mode ofthe central portion is illuminated differently from the illuminationmode other than the central portion.

In the example of FIG. 17, the hologram recording medium 30 has threehologram areas 32 corresponding to three laser beams that emit light inred, green, or blue, in the hologram area 32 for red, the entire regionthereof is scanned with the corresponding laser beam, and in thehologram area 32 for green and blue, excluding a part thereof, scanningis performed with the corresponding laser beam. In FIG. 17, in each ofthe hologram areas 32, a part where the corresponding laser beam is notscanned is shown in white. These hollow portions correspond to thecentral portion 10 a in the illumination zone 10. Since the red laserbeam scans the entire region of the corresponding hologram area 32, thered laser beam illuminates the entire region of the illumination zone10. The green and blue laser beams illuminate a part other than thecentral portion 10 a in the illumination zone 10 in order to scan theportion other than the hollow portion in the corresponding hologram area32. As a result, the central portion 10 a in the illumination zone 10 isilluminated in red, and the illumination zone 10 other than the centralportion 10 a is mixed with illumination light of red, green and blue andilluminated in white.

In FIG. 17, the central portion 10 a is formed in a rectangular shape,but since the shape of the central portion 10 a can be changedarbitrarily, it is also possible to display information in the centralportion 10 a. Therefore, for example, the information in the second area17 can be displayed by the central portion 10 a in FIG. 17 and the firstarea 15 can be illuminated in the illumination zone 10 other than thecentral portion 10 a. Actually, the information of the second area 17 isnot necessarily displayed using the central portion 10 in theillumination zone 10 as shown in FIG. 17.

On the other hand, in FIG. 18, in any of the three hologram areas 32, alaser beam scans a region other than the region corresponding to thecentral portion 10 a in the illumination zone 10. For this reason, thecentral portion 10 a in the illumination zone 10 is a non-illuminationzone that is not illuminated by any color.

In order to individually control the timing of the three laser beams, byarbitrarily adjusting the timing of the three laser beams, the timingcontrol unit 5 can illuminate an arbitrary place in the illuminationzone 10 with an arbitrary color. If the illumination mode inside theillumination zone 10 is arbitrarily adjusted, depending on theillumination mode, it becomes possible to illuminate an arbitrarypartial region in the actual illumination area illuminated with thelaser beam passing through the illumination zone 10 in an arbitraryillumination mode.

Each of the element hologram areas 31 for the first diffusion region 16can be produced by using, for example, scattered light from a realscattering plate as object light. More specifically, when the hologramphotosensitive material which is the base of the hologram recordingmedium 30 is illuminated with reference light and object light made ofcoherent light beam having coherency with each other, an interferencefringe due to interference of these light beams is formed on thehologram photosensitive material, and the hologram recording medium 30is manufactured. A laser beam which is coherent light beam is used asthe reference light, and scattered light of an isotropic scatteringplate which is available at low cost, for example, is used as the objectlight.

By illuminating the hologram recording medium 30 with a laser beam fromthe focal position of the reference light used for manufacturing thehologram recording medium 30, a reproduced image of the scattering plateis generated at the arrangement position of the scattering plate whichis the source of the object light used in manufacturing the hologramrecording medium 30. When the scattering plate which is the source ofthe object light used for manufacturing the hologram recording medium 30has uniform surface scattering, a reproduced image of the scatteringplate obtained by the hologram recording medium 30 is also a uniformplane illumination, and a region where the reproduced image of thisscattering plate is generated is the illumination zone 10.

Each element hologram area 31 for the second diffusion region 18 fordisplaying information in the second area 17 in the hologram recordingmedium 30 is formed by using a scattering plate on which an image ofinformation has been formed in advance, and Stripe can be formed.

In the hologram recording medium 30 according to the present embodiment,it is necessary to perform illumination in the first area 15 andinformation display in the second area 17, so that the interferencefringe becomes complicated. Without using actual object light andreference light, such a complicated interference fringe pattern can bedesigned using a computer based on the scheduled wavelength and incidentdirection of the reconstruction illumination light and the shape andposition of the image to be reproduced. The hologram recording medium 30thus obtained is also called a computer generated hologram (CGH). Inaddition, a Fourier transform hologram having the same diffusion anglecharacteristic at each point on each element hologram area 18 may beformed by computer synthesis. Furthermore, an optical member such as alens may be provided on the rear side of the optical axis of theillumination zone 10 to set the size and position of the actualillumination area.

One advantage of providing the hologram recording medium 30 as theoptical device 3 is that the energy density of the laser beam can bereduced by diffusion, and in addition, another advantage is that sincethe hologram recording medium 30 can be used as a directivity surfacelight source, the luminance on the light source surface for achievingthe same illuminance distribution can be reduced compared with theconventional lamp light source (point light source). Whereby, the safetyof the laser beam can be improved, and there is no possibility that ahuman eye will be adversely affected even if the laser beam that haspassed through the illumination zone 10 is viewed directly with thehuman eye.

In the examples shown in FIGS. 14 to 18, the hologram areas 32 for red,green and blue are arranged adjacent to each other along the incidentsurface of each hologram area 32 as shown in FIG. 19. In FIG. 19, thehologram area 32 for red is denoted by 32 r, the hologram area 32 forgreen is denoted by 32 g, and the hologram area 32 for blue is denotedby reference numeral 32 b.

In this way, in addition to arranging the three hologram areas 32adjacent along the incident surface, as shown in FIG. 20, the hologramrecording medium 30 in which the respective hologram areas 32 arearranged in the stacking direction may be used. In this case, theinterference fringe pattern of each hologram area 32 is formed in thelayer of each hologram area 32. In order to ensure that the laser beamreaches, without loss as much as possible, from the surface of thehologram recording medium 30 on which the laser beam from the lightscanning device 6 is incident to the hologram area 32 on the far side,it is desirable to make the visible light transmittance of each hologramarea 32 as high as possible. Further, when the interference fringepattern is formed at a position overlapping in the stacking direction,the laser beam hardly reaches the layer deeper from the surface;therefore, as shown in FIG. 18, it is desirable to form the interferencefringe patterns in each layer while being shifted in the stackingdirection.

FIG. 14 shows an example in which the laser beam from the light scanningdevice 6 diffuses through the optical device 3, but the optical device 3may diffuse and reflect the laser beam. For example, when the hologramrecording medium 30 is used as the optical device 3, the hologramrecording medium 30 may be a reflection type or a transmission type.Generally, the reflection type hologram recording medium 30(hereinafter, reflection type holo) has high wavelength selectivity ascompared with the transmission type hologram recording medium 30(hereinafter, transmission type holo). That is, even when theinterference fringe pattern corresponding to different wavelengths islaminated the reflection type holo can diffract coherent light beam of adesired wavelength only in a desired layer. Also, the reflection typeholo is superior in that it is easy to remove the influence of zeroorder light. On the other hand, the transmission type holo has a widediffractable spectrum and a wide tolerance of the laser light source 4;however, when the interference fringe pattern corresponding to differentwavelengths is laminated, coherent light beam of a desired wavelength isdiffracted even in a layer other than the desired layer. Therefore, ingeneral, it is difficult to form a transmission type holo with alaminated structure.

As a specific form of the hologram recording medium 30, a volumehologram recording medium 30 using a photopolymer may be used, avolumetric hologram recording medium 30 of a type that performsrecording using a photosensitive medium containing a silver saltmaterial may be used, and a relief type (emboss type) hologram recordingmedium 30 may be used.

The specific form of the optical device 3 is not limited to the hologramrecording medium 30, and may be various diffusion members that can befinely divided into the plurality of element diffusion regions 19. Forexample, the optical device 3 may be configured using a lens array groupin which each element diffusion region 19 is a single lens array. Inthis case, a lens array is provided for each element diffusion region19, and the shape of each lens array is designed so that each lens arrayilluminates the partial region 10 b in the illumination zone 10. Atleast a part of the position of each partial region 10 b is different.As a result, similarly to the case where the optical device 3 isconfigured using the hologram recording medium 30, it is possible tochange the illumination color of only a part of the illumination zone 10or to prevent only a part from being illuminated.

In FIGS. 17 and 18, an example in which a part of the illumination inthe illumination zone 10 is stopped or a part of the illumination coloris changed is shown. However, another method for changing theillumination mode of a part of the illumination zone 10 is conceivable.For example, when the laser light source 4 has a plurality of lightsource units 7 that emit light in the same emission wavelength range,the light emission of a part of the light source units 7 may be stoppedso that the illumination intensity of a part of the inside of theillumination zone 10 is lower than the illumination intensity of thesurrounding area. Conversely, a part of the illumination intensity inthe illumination zone 10 may be higher than the surrounding illuminationintensity. In addition, a part of the inside of the illumination zone 10may be illuminated with flashing. Alternatively, a part of the color inthe illumination zone 10 may be changed continuously or intermittently.

FIG. 21 shows an example in which the illumination device 1 according tothe present embodiment is applied to a headlight 35 for a car. Since adriver 36 performs driving while watching the front of the car through awindshield 37, when the headlight 35 is lit, the driver 36 visuallyrecognizes the area illuminated by the headlight 35. In the presentembodiment, the first area 15 and the second area 17 are provided in thearea illuminated by the headlight 35, the first area 15 performsillumination as the normal headlight 35, and in the second area 17,various kinds of information are displayed as necessary. The first area15 is a wide area up to several tens of meters on the front side of thecar, while the second area 17 is provided in a limited area, forexample, several meters away from the viewpoint position of the driver36. The size and position of the first area 15 and the second area 17are arbitrarily variably adjusted by an interference fringe patternformed in each of the element hologram areas 31 in the first diffusionregion 16 and the second diffusion region 18.

The information display of the second area 17 can be used instead of theexisting head-up display. In the existing head-up display, although avirtual image is formed several meters ahead of the windshield 37 byusing a projector and a magnifying mirror provided in a dashboard,according to the present embodiment, information can be displayed in thesecond area 17 only by the headlight 35 without using a projector and amagnifying glass. Further, according to the present embodiment, sincethe size and position of the information displayed in the second area 17can be arbitrarily adjusted by the optical device 3, information can bedisplayed in a desired size in a place where the driver 36 is mostvisible.

FIG. 22 is a view showing a specific example of information in thesecond area 17 displayed using the headlight 35. FIG. 22A shows anexample of displaying information on an arrow indicating a travelingdirection of the car. FIG. 22B shows an example of displayinginformation prohibiting left turn. FIG. 22C shows an example ofdisplaying information on the traveling direction of the car on athree-way road. In FIG. 22C, not only an X mark indicating prohibitionof traveling but also the direction of the car to travel and the otherdirections change the color of the arrow to call attention of the driver36.

For each piece of information shown in FIG. 22, the interference fringepattern corresponding to each information is previously formed in eachelement hologram are 31 in the second diffusion region 18 in thehologram recording medium 30, and by controlling the element hologramarea 31 to be irradiated with the laser beam by the timing control unit5, it is possible to display desired information in the second area 17at a desired timing.

Note that the information displayed in the second area 17 is not limitedto that shown in FIG. 22. As described above, arbitrary information canbe displayed in an arbitrary size and at the arbitrary position by theinterference fringe pattern formed in the element hologram area 31corresponding to the second diffusion region 18.

In the above-described fifth embodiment, an example in which informationsuch as arrows is displayed using the second diffusion region 18 in theoptical device 3 has been described. However, each of the elementdiffusion regions 19 in the second diffusion region 18 may performillumination with a shape corresponding to the display form ofinformation such as an arrow and like the element diffusion regions 19in the first diffusion region 16, for example, may perform rectangularillumination. FIG. 23 shows an example in which each element diffusionregion 19 in the second diffusion region 18 performs rectangularillumination and displays the information on an arrow by combining theillumination areas of each element diffusion region 19. In this way,both the first diffusion region 16 of the optical device 3 and each ofthe element diffusion regions 19 in the second diffusion region 18 mayperform illumination with a predetermined shape such as a rectangle.

FIG. 23 shows an example in which the size of the partial region 10 bformed by each element diffusion region 19 in the first diffusion region16 on the illumination zone 10, and the size of the partial region 10 bformed by each element diffusion region 19 in the second diffusionregion 18 on the illumination zone 10 are different from each other;however, the size and position of both partial regions 10 b arearbitrary.

As described above, in the fifth embodiment, since desired informationcan be displayed in the second area 17 at a desired timing whileperforming illumination of the first area 15 using coherent light beam,the illumination device 1 can be effectively utilized. Further, unlikethe existing head-up display, since a projector and a magnifying glassare unnecessary, and the size and display position of the information tobe displayed can be arbitrarily adjusted by the optical device 3, it ispossible to display more clear and powerful information while having asimple optical configuration than the existing head up display.

Furthermore, the light scanning device 6 scans laser beam in eachelement diffusion region 19, and the laser beam incident on each pointin each element diffusion region 19 illuminates the entire region of thepartial region 10 b. Therefore, the incident angle of the laser beam inthe partial region 10 b in the illumination zone 10 changes with thelapse of time, so that a speckle in the illumination zone 10 is lessnoticeable.

Sixth Embodiment

FIG. 24 is a view showing a schematic configuration of the illuminationdevice 1 according to the sixth embodiment of the present invention. Theillumination device 1 in FIG. 24 is obtained by adding an informationselection unit 21 in FIG. 14. The information selection unit 21 selectsinformation to be displayed in the second area 17. The informationselection unit 21 may receive a signal from a controller (not shown),various sensors, or the like and may select information based on thesignal, and may select information based on information input by theuser through an input device (not shown). Alternatively, the informationselection unit 21 may select information according to the processingalgorithm thereof. As described above, the specific processing procedurefor the information selection unit 21 to select the information to bedisplayed in the second area 17 is arbitrary.

In order to display the information selected by the informationselection unit 21 in the second area 17, the timing control unit 5controls the timing of scanning each element hologram area 31corresponding to the second diffusion region 18. More specifically,laser beam is scanned on the element hologram area 31 on which theinterference fringe pattern corresponding to the information selected bythe information selection unit 21 is formed.

Further, the information selection unit 21 may switch information to beselected depending on whether the vehicle is traveling or stopped. Forexample, while the vehicle is traveling, the route guidance informationof the vehicle as shown in FIG. 22 is displayed, and when the vehiclestops, various information may be displayed for advertisement promotion,or for improvement of designability and decorativeness by using theheadlight 35. Specific information in this case is, for example, a brandname of a vehicle, a manufacturer name, a model name, and the like. Thisalso serves as advertisement of a vehicle, and can give superiority tothe owner of the vehicle.

Furthermore, an object detection unit (not shown) for detecting anobject located in the area illuminated in the first area 15 may beprovided, and the information selection unit 21 may select informationmatching the position of the detected object. In this case, even if theobject moves, it is possible to display the information of the secondarea 17 according to the position of the object.

FIG. 25 is a view showing a schematic configuration of the illuminationdevice 1 showing a first modification of FIG. 24. The illuminationdevice 1 in FIG. 25 is obtained by adding a route information acquiringunit 22 in FIG. 24. The illumination device 1 in FIG. 25 is assumed tobe mounted on a vehicle, and the illumination device 1 of FIG. 25 is,for example, the headlight 35.

The route information acquiring unit 22 acquires route information onwhich the vehicle is to travel. The route information acquired by theroute information acquiring unit 22 is generated by performing a routesearch from the current location of the vehicle or the departure placeto the destination inside or outside the illumination device 1, and forexample, the route information is generated by a navigation device (notshown).

The information selection unit 21 in FIG. 25 selects information to bedisplayed in the second area 17 based on the route information acquiredby the route information acquiring unit 22. For example, as shown inFIG. 22A, in the case where the vehicle is to turn right at a branchroad, arrow information on the right turn is selected. Similarly, theinformation selection unit 21 in FIG. 25 can also select information asshown in FIG. 22B or FIG. 22C based on the route information.

FIG. 26 is a view showing a schematic configuration of the illuminationdevice 1 showing a second modification of FIG. 24. The illuminationdevice 1 in FIG. 26 is obtained by adding the map information acquiringunit 23 in FIG. 24. The illumination device 1 in FIG. 26 is also assumedto be mounted on the vehicle, and the illumination device 1 in FIG. 26is, for example, the headlight 35.

The map information acquiring unit 23 acquires map information aroundthe current position of the vehicle. The map information incoming unit23 detects the current position of the vehicle by using, for example, aGPS sensor or the like inside or outside the illumination device 1 andacquires map information around the current position from the mapinformation database, for example.

The information selection unit 21 in FIG. 26 selects information to bedisplayed in the second area 17 based on the map information acquired bythe map information acquiring unit 23. As a result, information such asthe arrow or the like shown in FIG. 22 can be selected.

Note that the route information acquiring unit 22 in FIG. 25 and the mapinformation acquiring unit 23 in FIG. 26 may be provided in theillumination device 1.

As described above, in the sixth embodiment, since the informationselected by the information selection unit 21 at a desired timing isdisplayed in the second area 17, while illuminating the first area 15,information to be displayed in the second area 17 can be switched asnecessary. Therefore, when the illumination device 1 according to thepresent embodiment is applied to, for example, the headlight 35 for thevehicle, information required by the driver 36 can be appropriatelydisplayed in the second area 17 while the vehicle is traveling or thevehicle is stopped.

The illumination device 1 according to the fifth and sixth embodimentsmay be mounted not only in the vehicle but also in a specific place. Inaddition, even when mounted on a vehicle, the vehicle is not limited toa car, but may be various moving bodies such as an aircraft, a train, aship, a diving vehicle and the like.

Seventh Embodiment

FIG. 27 is a view showing a schematic configuration of the illuminationdevice 1 according to the seventh embodiment of the present invention.The illumination device 1 in FIG. 27 includes the irradiation device 2,the optical device 3, and an optical shutter 25. The irradiation device2 has the laser light source 4, a beam diameter expansion member 26, anda collimating optical system 27.

The laser light source 4 emits coherent light beam, that is, laser beam.The laser light source 4 may be provided with a plurality of lightsource units with different emission wavelength ranges, but may beconfigured to have one or more light source units that emit laser beamin a single wavelength range. In this embodiment, an example in whichone or more light source units that emit laser beam in a singlewavelength range is provided will be described.

The beam diameter expansion member 26 expands the beam diameter of thelaser beam emitted from the laser light source 4, and for example, isconfigured by an optical member including a convex lens. That is, thebeam diameter expansion member 26 acts to diffuse a laser beam.

The collimating optical system 27 collimates a laser beam diffused bythe beam diameter expansion member 26 and guides the laser beam to theincident surface of the optical shutter 25.

The optical device 3 has the incident surface 3 a on which the laserbeam is incident, and diffuses the laser beam incident on the incidentsurface 3 a to illuminate a predetermined area, that is, theillumination zone 10. Since the laser beam for illuminating theillumination zone 10 is diffused beyond the illumination zone 10, ifthere is no object that blocks laser beam at the position of theillumination zone 10, the laser beam further diffuses.

Here, the illumination zone 10 is the illumination zone 10 of a nearfield illuminated by overlapping each diffusion region 14 in the opticaldevice 3. The illumination area of the far field is often expressed as adiffusion angle distribution in the angular space rather than the actualsize of the illumination zone 10. In the present specification, the term“illumination zone 10” includes the diffusion angle area in the angularspace in addition to the actual illuminated area (illumination area).Therefore, the illumination area illuminated by the illumination device1 in FIG. 27 can be a much wider area than the illumination zone 10 ofthe near field shown in FIG. 27.

The optical shutter 25 switches the transmittance of the laser beamincident on the optical device 3 or the laser beam diffused by theoptical device 3. In the case of FIG. 27, since an optical shutter 25 isprovided in front of the optical device 3 in the direction of theoptical axis, the optical shutter 25 functions to switch thetransmittance of the laser beam incident on the optical device 3. Aswill be described later, it is also possible to replace the arrangementof the optical shutter 25 and the optical device 3 with each other.

FIG. 28 is a view showing the detailed configuration of the opticalshutter 25 and the optical device 3 in the seventh embodiment. As shownin FIG. 28, the optical device 3 has the plurality of element diffusionregions 19, each of which diffuses laser beam individually. The laserbeam incident on and diffused into each element diffusion region 19illuminates a partial region in the illumination zone 10. In thisspecification, a corresponding region in the illumination zone 10illuminated by one element diffusion region 19 is called the partialregion 10 a. Each of the different element diffusion regions 19illuminates the partial region 10 a in which at least a part in theillumination zone 10 is different. Thus, when the plurality of elementdiffusion regions 19 are combined, the entire region of the illuminationzone 10 can be illuminated.

The optical shutter 25 has a plurality of element shutter units 28corresponding to the plurality of element diffusion regions 19. That is,each of the plurality of element diffusion regions 19 is associated withthe separate element shutter unit 28, and the laser beam transmittedthrough one element shutter unit 28 is incident on the correspondingelement diffusion region 19. Each of the plurality of element shutterunits 28 switches the transmittance of the laser beam incident on thecorresponding element diffusion region 19 or the laser beam diffused bythe corresponding element diffusion region 19. In FIG. 28, the elementshutter unit 28 having a high transmittance is shown in white, and theelement shutter unit 28 with a low transmittance is shown by diagonallines. It is desirable that the optical shutter 25 be arranged as closeas possible to the optical device 3.

In the examples of FIGS. 27 and 28, the laser beam whose beam diameteris expanded by the beam diameter expansion member 26 is uniformlyincident on all the element shutter units 28 in the optical shutter 25.Each element shutter unit 28 switches the transmittance of the incidentlaser beam. For example, when the element shutter unit 28 transmitslaser beam, the laser beam is incident on the element diffusion region19 corresponding to the element shutter unit 28. In this way, byswitching the transmittance for each of the element shutter units 28 inthe optical shutter 25, whether or not the laser beam is made incidenton the optical device 3 can be switched for each element diffusionregion 19 in the optical device 3.

Switching of the transmittance performed by each element shutter unit 28is, in a simple example, two types of switching, that is, whether thelaser beam is transmitted or blocked. In this case, only when theelement shutter unit 28 transmits a laser beam, the laser beam isincident on the corresponding element diffusion region 19, and thiselement diffusion region 19 illuminates the corresponding partial region10 a in the illumination zone 10. Therefore, by individually switchingthe plurality of element shutter units 28 in the optical shutter 25, itis possible to individually switch whether or not to illuminate eachpartial region 10 a in the illumination zone 10.

In this manner, whether or not to illuminate can be variably controlledfor each partial region 10 a in the illumination zone 10 by the opticalshutter 25; therefore, it is possible to arbitrarily switch theillumination mode of the illumination zone 10. The illumination modehere means to switch the illumination/non-illumination for each partialregion 10 a in the illumination zone 10.

By arbitrarily switching the illumination mode of the illumination zone10, it is possible to display some kind of information in theillumination zone 10 or have unique design characteristics depending onthe illumination mode of the illumination zone 10. The informationdisplayed by the illumination of the illumination zone 10 is, forexample, at least one of a picture, a pattern, a letter, a number and asymbol, and the specific content of the information is not particularlylimited. In the present embodiment, since it is assumed that laser beamof a single wavelength range is used, color display of informationcannot be performed; however, even for a single color, it is possible todisplay various kinds of information for the purpose of giving designsand decorativeness, the purpose of calling attention, the purpose ofguidance display, the purpose of advertisement publicity, and the like.

Since switching of the optical shutter 25 can be performed in anarbitrary manner at an arbitrary timing, the illumination mode in theillumination zone 10 can also be arbitrarily variably adjusted. Thereby,it is possible to arbitrarily change the illumination mode of theillumination zone 10 without increasing the cost.

The optical shutter 25 can be realized by, for example, a liquid crystalshutter. The liquid crystal shutter has a plurality of liquid crystalcells corresponding to the plurality of element shutter units 28. FIG.29 is a view schematically showing the structure of one liquid crystalcell 41. The liquid crystal cell 41 in FIG. 29 includes a liquid crystalmaterial 43 filled between two alignment films 42 and two polarizationfilters 44 arranged outside the respective alignment films 42. FIG. 29shows an example using the TN type liquid crystal material 43. When novoltage is applied between the two alignment films 42, the liquidcrystal material 43 is in a twisted state as shown in FIG. 29A, whilethe light passes through the two alignment films 42, the polarizationstate of the light changes, and as a result, the light passes throughthe polarization filter 44. On the other hand, when a voltage is appliedbetween the two alignment films 42, as shown in FIG. 29B, the liquidcrystal material 43 is aligned in one direction and the polarizationstate does not change even if light passes between the two alignmentfilms 42, and as a result, the light cannot pass through thepolarization filter 44.

When the laser beam incident on the optical shutter 25 is polarized inadvance, one polarization filter 44 in the liquid crystal shutterbecomes unnecessary. Further, since the liquid crystal shutter hasvarious systems, it is not limited to the structure shown in FIG. 29. Ashutter like a liquid crystal shutter in which a cell capable ofelectrically switching the transmittance is arranged in a matrix form isreferred to as a multi-cell shutter in this specification.

Further, the optical shutter 25 is not necessarily limited to amulti-cell shutter such as a liquid crystal shutter. For example, amechanical shutter that mechanically opens and closes such as a MicroElectro Mechanical Systems (MEMS) shutter or the like, or an electronicshutter such as an electromagnetic shutter using a solenoid may be used.

Incidentally, the optical shutter 25 is not limited to only switchingthe transmission/blocking of a laser beam, but may change thetransmittance of a laser beam intermittently or continuously. Forexample, in the case of the liquid crystal shutter as shown in FIG. 29,by changing the voltage applied between the alignment films 42, thetransmittance of the laser beam can be continuously changed. Also, whenusing the MEMS shutter, the electromagnetic shutter, or the like, byintermittently or continuously switching the opening area of the shutterunit, the transmittance of the laser beam can be intermittently orcontinuously changed.

In this way, by intermittently or continuously switching thetransmittance of the laser beam by the optical shutter 25, it ispossible to not only switch the illumination/non-illumination for eachpartial region 10 a in the illumination zone 10 but also adjust theillumination intensity for each partial region 10 a. Thus, theillumination mode in the illumination zone 10 can be variably and finelyadjusted. Here, the illumination mode is to arbitrarily switch ON/OFF ofillumination and intensity of illumination intensity for each partialregion 10 a in the illumination zone 10.

The optical device 3 is configured using, for example, the hologramrecording medium 30. As shown in FIG. 2, the hologram recording medium30 has a plurality of element hologram areas 31 corresponding to theplurality of element diffusion regions 19. In each element hologram area31, an interference fringe pattern is formed. When the laser beam isincident on the interference fringe pattern, the laser beam isdiffracted by the interference fringe pattern and illuminates thecorresponding region in the illumination zone 10.

In FIG. 2, the example in which each element diffusion region 19 in theoptical device 3 illuminates the corresponding partial region 10 a inthe illumination zone 10 has been described; however, as shown in FIG.30, the first diffusion region 16 including at least one elementdiffusion region 19 that illuminates, in the optical device 3, thecorresponding partial region 10 a in the illumination zone 10, and thesecond diffusion region 18 including at least one element diffusionregion 19 for displaying predetermined information in the correspondingpartial region 10 a in the illumination zone 10 may be provided in theoptical device.

In FIG. 30, an example is shown in which the partial region 10 a in theillumination zone 10 illuminated by the first diffusion region 16 andthe partial region 10 a in the illumination zone 10 displayed asinformation by the second diffusion region 18 are provided separately;however, these partial regions 10 a may overlap each other.

The information displayed in the corresponding partial region 10 a inthe illumination zone 10 is changed by at least one of hue, brightnessand saturation by each element diffusion region 19 in the seconddiffusion region 18. More specifically, the information displayed in thecorresponding partial region 10 a in the illumination zone 10 is, forexample, at least one of a picture, a pattern, a letter, a number and asymbol, and the specific content of the information is not particularlylimited. Information displayed in the corresponding partial region 10 ain the illumination zone 10 by each element diffusion region 19 in thesecond diffusion region 18 is, for example, performed for the purpose ofgiving designs and decorativeness, the purpose of calling attention, thepurpose of guidance display, the purpose of advertisement publicity, andthe like.

In the case of forming the optical device 3 with the hologram recordingmedium 30, in each element diffusion region 19 in the first diffusionregion 16, the corresponding interference fringe pattern is formed inadvance so as to illuminate the corresponding partial region 10 a in theillumination zone 10. Similarly, in each element diffusion region 19 inthe second diffusion region 18, the corresponding interference fringepattern is formed in advance so that predetermined information isdisplayed in the corresponding partial region 10 a in the illuminationzone 10.

By appropriately forming the appropriate interference fringe pattern ineach element hologram area 31 in the hologram recording medium 30 inthis manner, the illumination or the predetermined information displaycan be performed for each partial region 10 a in the illumination zone10 by the laser beam diffracted at each element hologram area 31.

In the case where the first diffusion region 16 and the second diffusionregion 18 are provided in the optical device 3 as shown in FIG. 30, theoptical shutter 25 has the element shutter units 28 corresponding toeach element diffusion region 19 in the first diffusion region 16 andeach element diffusion region 19 in the second diffusion region 18.Therefore, by controlling switching of each element shutter unit 28,each element diffusion region 19 in the first diffusion region 16 canindividually control the illumination mode of the corresponding partialregion 10 a in the illumination zone 10, and each element diffusionregion 19 in the second diffusion region 18 can individually control theillumination mode of the information displayed in the correspondingpartial region 10 a in the illumination zone 10.

In the present embodiment, laser beam is used as an illumination lightsource, so that speckle may be visually recognized in the illuminationof the illumination zone 10. In order to make speckle less noticeable,for example, the optical shutter 25 and the optical device 3 may bevibrated in a one-dimensional or two-dimensional direction at apredetermined cycle. Thus, the incident position and the incident angleof the laser beam incident on the optical device 3 through the opticalshutter 25 can be changed with the lapse of time. The laser beamincident on one element diffusion region 19 illuminates the commonpartial region 10 a in the illumination zone 10 even if the laser beamis incident on any position in the element diffusion region 19. That is,this means that the incident angle of the laser beam incident on eachpoint of a partial region 10 a changes with the lapse of time. By makingthe vibration period sufficiently fast, it is possible to make thechange of the incident angle a speed which cannot be resolved by humaneyes, and as a result, the scattering pattern of coherent light beamhaving no correlation is multiplexed and observed in the human eye.Therefore, the speckle generated corresponding to each scatteringpattern is overlapped and averaged, and is observed by the observer. Asa result, in the illumination zone 10, speckle becomes less conspicuous.

When the illumination device 1 according to the present embodiment isapplied to the illumination device 1 for an in-vehicle such as aheadlight, the car constantly vibrates in accordance with the state ofthe engine and the road surface during traveling. Therefore, the specklebecomes inconspicuous to some extent without providing a vibrationmechanism for anti-speckle in the illumination device 1.

In FIG. 27, the laser beam whose beam diameter is expanded by the beamdiameter expansion member 26 is incident on the optical shutter 25, andthe light transmitted through the optical shutter 25 is incident on theoptical device 3. However, the arrangement of the optical shutter 25 andthe optical device 3 may be reversed.

FIG. 31 is a view showing a schematic configuration of the illuminationdevice 1 in which the arrangement of the optical shutter 25 and theoptical device 3 is reversed from that in FIG. 27. In FIG. 31, the laserbeam whose beam diameter is expanded by the beam diameter expansionmember 26 is incident on the optical device 3. The optical device 3 hasa plurality of element diffusion regions 19, and each element diffusionregion 19 diffuses the incident laser beam. The laser beam diffused ineach element diffusion region 19 is incident on the correspondingelement shutter unit 28 in the optical shutter 25. By switching thetransmittance individually by each element shutter unit 28, it ispossible to switch the illumination mode for each partial region 10 a inthe illumination zone 10 as in FIG. 27.

In FIG. 31, the optical shutter 25 is disposed on the optical axis rearside of the optical device 3, but the optical device 3 diffuses theincident laser beam. Therefore, if the distance between the opticaldevice 3 and the optical shutter 25 is large, the laser beam leakingfrom the optical shutter 25 will be emitted. Therefore, in the case ofthe configuration of FIG. 31, it is desirable to make the opticalshutter 25 as close as possible to the optical device 3.

As described above, in the seventh embodiment, since the plurality ofelement shutter units 28 are provided in the optical shutter 25 inassociation with the plurality of element diffusion regions 19 in theoptical device 3, it is possible to switch the illumination mode of theillumination zone 10 illuminated by the laser beam diffused by theplurality of element diffusion regions 19 for each partial region 10 ain the illumination zone 10. Therefore, although the illumination colorof the illumination zone 10 cannot be changed, it is possible to makethe illumination mode of the illumination zone 10 excellent indesignability or to display some information by the illumination zone10.

In addition, switching of the illumination mode of the illumination zone10 can be performed at an arbitrary timing by the optical shutter 25,and the illumination mode of the illumination zone 10 can be easilyswitched.

Eighth Embodiment

In the eighth embodiment described below, color separation is performedby the optical shutter 25.

FIG. 32 is a view showing a schematic configuration of the illuminationdevice 1 according to the eighth embodiment of the present invention,and FIG. 33 is a view showing a detailed configuration of the opticalshutter 25 and the optical device 3 in the eighth embodiment.

The laser light source 4 in the illumination device 1 in FIG. 32 has aplurality of light source units 4 r, 4 g, 4 b that emit a plurality ofcoherent light beams, i.e., laser beams having different emissionwavelength ranges. The plurality of light source units 5 may be providedseparately or may be a light source module in which the plurality oflight source units 4 r, 4 g, 4 b are arranged side by side on a commonsubstrate. It is sufficient that the laser light source 4 of the presentembodiment has at least two light source units having different emissionwavelength ranges, and the number of types of emission wavelength rangesmay be two or more. In order to increase the emission intensity, theplurality of light source units may be provided for each emissionwavelength range.

For example, when the laser light source 4 has the light source unit 4 rin the red emission wavelength range, the light source unit 4 g in thegreen emission wavelength range, and the light source unit 4 b in theblue emission wavelength range, it is possible to generate whiteillumination light by overlapping three laser beams emitted from thelight source units 4 r, 4 g, 4 b.

The optical device 3 has a plurality of diffusion regions 17corresponding to the plurality of laser beams as shown in FIG. 33. Thecorresponding laser beam is incident on each diffusion region 17. Eachdiffusion region 17 diffuses the incident laser beam and illuminates theentire region of the illumination zone 10 as a whole. Each diffusionregion part 17 has the plurality of element diffusion regions 19. Eachelement diffusion region 19 diffuses the incident laser beam andilluminates a partial region 10 a in the illumination zone 10. At leasta part of the partial region 10 a differs for each element diffusionregion 19.

The optical shutter 25 has the plurality of element shutter units 28corresponding to the plurality of element diffusion regions 19 for eachof the plurality of diffusion regions. Therefore, in a case where it isdesired to switch the illumination color of the entire region of theillumination zone 10 illuminated with one color by one diffusion regionirradiated with laser beam of a certain wavelength range at once,switching may be performed using a plurality of element shutter units 28corresponding to one diffusion region as one set.

In addition, when it is desired to switch the illumination color of anarbitrary partial region 10 a in the illumination zone 10, the elementshutter units 28 corresponding to any element diffusion regions 19 in anarbitrary diffusion region may be individually switched.

The optical device 3 is configured using, for example, the hologramrecording medium 30. As shown in FIG. 33, the hologram recording medium30 has the plurality of hologram areas 32 corresponding to the pluralityof diffusion regions. Each of the hologram areas 32 is providedcorresponding to each of the plurality of laser beams having differentemission wavelength ranges. Each hologram area 32 has an incidentsurface on which the corresponding laser beam is incident. The laserbeams incident on the incident surface of each hologram area 32 arediffused to illuminate the illumination zone 10. For example, when thehologram recording medium 30 has three hologram areas 32, the laser beamdiffused in each hologram area 32 illuminates the entire region of theillumination zone 10.

FIG. 33 shows an example in which three hologram areas 32 are providedin association with three laser beams that emit light in red, blue, orgreen. However, the hologram recording medium 30 according to thepresent embodiment may have two or more hologram areas 32 in associationwith two or more laser beams having different emission wavelengthranges. As shown in FIG. 33, when the hologram recording medium 30 hasthree hologram areas 32 corresponding to three laser beams that emitlight in red, blue, or green, each hologram area 32 illuminates theentire region of the illuminated region 10, so that when the three laserbeams emit light, the illumination zone 10 is illuminated with whitelight.

The size, that is, the area of each hologram area 32 in the hologramrecording medium 30 is not necessarily the same. Even if the sizes ofthe respective hologram areas 32 are different, by individuallyadjusting the interference fringe formed on the incident surface of eachhologram area 32, each hologram area 32 can illuminate the commonillumination zone 10.

Each of the plurality of hologram areas 32 has the plurality of elementhologram areas 31 corresponding to the plurality of element diffusionregions 19. Each of the plurality of element hologram areas 31illuminates the partial region 10 a in the illumination zone 10 bydiffusing the incident laser beam. At least a part of the partial region10 a illuminated by each element hologram area 31 is different for eachelement hologram area 31. That is, the partial regions 10 a illuminatedby the different element hologram areas 31 are at least partiallydifferent from each other.

An interference fringe pattern is formed on an incident surface of eachelement hologram area 31. Therefore, the laser beam incident on theincident surface of each element hologram area 31 is diffracted by theinterference fringe pattern on the incident surface, and illuminates thecorresponding partial region 10 a on the illumination zone 10. Byadjusting the interference fringe pattern variously, it is possible tochange the traveling direction of the laser beam diffracted or diffusedin each element hologram area 31.

In the case where the optical device 3 is configured by the hologramrecording medium 30, the optical shutter 25 has the plurality of elementshutter units 28 corresponding to the plurality of element hologramareas 31 for each of the plurality of hologram areas 32. That is, eachelement shutter unit 28 of the optical shutter 25 is associated with oneelement hologram area 31 in the hologram recording medium 30 for eachhologram area 21.

Accordingly, for each laser beam having different wavelength ranges, theoptical shutter 25 according to the eighth embodiment can switch all thecorresponding illumination modes of the illumination zone 10 at once byswitching the corresponding plurality of element shutter units 28 atonce. In addition, the optical shutter 25 can switch the illuminationmode including the illumination color for each partial region 10 a inthe illumination zone 10 by individually switching the transmittance foreach element shutter unit 28.

Also in the eighth embodiment, as described with reference to FIG. 30,for each of the plurality of laser beams having different wavelengthranges, the first diffusion region 16 for illumination and the seconddiffusion region 18 for information display may be provided in eachdiffusion region in the optical device 3. In this case, the opticalshutter 25 has the element shutter unit 28 in association with eachelement diffusion region 19 in the first diffusion region 16 and eachelement diffusion region 19 in the second diffusion region 18.

Thus, it is possible to individually control the illumination mode ineach partial region 10 a for illumination in the illumination zone 10and the illumination mode in each partial region 10 a for informationdisplay.

As described above, in the eighth embodiment, the plurality of diffusionregions 17 irradiated with laser beams having different wavelengthranges are provided in the optical device 3, and each diffusion region17 has the plurality of element diffusion regions 19 and the pluralityof element shutter units 28 corresponding to the plurality of elementdiffusion regions 19 are provided in the optical shutter 25. Therefore,by individually switching the transmittance for each element shutterunit 28, it is possible to switch and control the illumination modeincluding the illumination color for each partial region 10 a in theillumination zone 10.

In the case where the optical device 3 according to the first and eighthembodiments is realized by the hologram recording medium 30, it isnecessary to form the hologram recording medium 30 with the plurality ofelement hologram areas 31 and form the interference fringe pattern foreach element hologram area 31. Without using actual object light andreference light, the interference fringe pattern can be designed using acomputer based on the scheduled wavelength and incident direction of thereconstruction illumination light and the shape and position of theimage to be reproduced. The hologram recording medium 30 thus obtainedis also called a computer generated hologram (CGH). In addition, aFourier transform hologram having the same diffusion anglecharacteristic at each point on each element hologram area 3121 may beformed by computer synthesis. Furthermore, an optical member such as alens may be provided on the rear side of the optical axis of theillumination zone 10 to set the size and position of the actualillumination area.

One advantage of providing the hologram recording medium 30 as theoptical device 3 is that the optical energy density of the laser beamcan be reduced by diffusion, and in addition, another advantage is thatsince the hologram recording medium 30 can be used as a directivitysurface light source, the luminance on the light source surface forachieving the same illuminance distribution can be reduced compared withthe conventional lamp light source (point light source). This cancontribute to improving the safety of the laser beam, and even if thelaser beam having passed through the illumination zone 10 is vieweddirectly with a human eye, there is less possibility of adverselyaffecting the human eye as compared with the case of looking directly ata single point light source.

FIG. 27 shows an example in which the laser beam from the light scanningdevice 6 diffuses through the optical device 3, but the optical device 3may diffuse and reflect the laser beam. For example, when the hologramrecording medium 30 is used as the optical device 3, the hologramrecording medium 30 may be a reflection type or a transmission type.Generally, the reflection type hologram recording medium 30(hereinafter, reflection type holo) has high wavelength selectivity ascompared with the transmission type hologram recording medium 30(hereinafter, transmission type holo). That is, even when theinterference fringe pattern corresponding to different wavelengths islaminated the reflection type holo can diffract coherent light beam of adesired wavelength only in a desired layer. Also, the reflection typeholo is superior in that it is easy to remove the influence of zeroorder light. On the other hand, the transmission type holo has a widediffractable spectrum and a wide tolerance of the laser light source 4.However, when the interference fringe pattern corresponding to differentwavelengths is laminated, coherent light beam of a desired wavelength isdiffracted even in a layer other than the desired layer. Therefore, ingeneral, it is difficult to form a transmission type holo with alaminated structure.

As a specific form of the hologram recording medium 30, a volumehologram recording medium 30 using a photopolymer may be used, avolumetric hologram recording medium 30 of a type that performsrecording using a photosensitive medium containing a silver saltmaterial may be used, and a relief type (emboss type) hologram recordingmedium 30 may be used.

The specific form of the optical device 3 is not limited to the hologramrecording medium 30, and may be various diffusion members that can befinely divided into the plurality of element diffusion regions 19. Forexample, the optical device 3 may be configured using a lens array groupin which each element diffusion region 19 is a single lens array. Inthis case, a lens array is provided for each element diffusion region19, and the shape of each lens array is designed so that each lens arrayilluminates the partial region 10 a in the illumination zone 10. Atleast a part of the position of each partial region 10 a is different.As a result, similarly to the case where the optical device 3 isconfigured using the hologram recording medium 30, illumination can beperformed for each partial region 10 a in the illumination zone 10.

Ninth Embodiment

FIG. 34 is a view showing a schematic configuration of the illuminationdevice 1 according to the ninth embodiment of the present invention.FIG. 35 is a plan view of the optical device 3 in the illuminationdevice 1 in FIG. 34.

As shown in FIG. 34, the illumination device 1 according to the presentembodiment includes a coherent light source 4 that emits coherent lightbeam, the optical device 3 that holds a plurality of diffusion regions(diffusion elements) 19 for diffusing coherent light beam, a drivingunit 51 that moves the optical device 3 such that each of the pluralityof diffusion regions 19 sequentially reaches an illumination position 52of the coherent light beam, and a timing control unit 5 that controlsthe timing of the coherent light beam.

As the coherent light source 4, for example, a semiconductor laser lightsource can be used. In order to increase the light emission intensity,the coherent light source 4 may be configured to collect the coherentlight beam emitted from the plurality of laser light sources with thefiber and then emit the light toward the illumination position 52.

The timing control unit 5 controls the timing at which coherent lightbeam is emitted from the coherent light source 4.

Specifically, for example, the timing control unit 5 controls whethercoherent light beam is emitted from the coherent light source 4, thatis, on/off of light emission. Alternatively, the timing control unit 5may switch whether or not to guide the coherent light beam emitted fromthe coherent light source 4 to the incident surface of the opticaldevice 3. In the latter case, an optical shutter unit (not shown) isprovided between the coherent light source 4 and the optical device 3,and the passing/blocking of coherent light beam is switched by theoptical shutter unit.

The optical device 3 has an incident surface on which coherent lightbeam is incident, and diffuses the coherent light beam incident on theincident surface to illuminate the predetermined illumination area 10.More specifically, the coherent light beam diffused by the opticaldevice 3 passes through the predetermined illumination area 10 and thenilluminates the actual illumination area.

Here, the predetermined illumination area 10 is the illumination area ofthe near field illuminated by the optical device 3. The illuminationarea of the far field is often expressed as a diffusion angledistribution in the angular space rather than the actual size of theillumination area. In the present specification, the term “predeterminedarea” includes a diffusion angle area in the angular space in additionto the actual illumination zone (illumination area). Therefore, theillumination area illuminated by the illumination device 1 in FIG. 34can be a much wider area than the illumination area 21 of near fieldshown in FIG. 34.

As shown in FIG. 35, the plurality of diffusion regions 19 are arrangedon the incident surface of the optical device 3.

In the illustrated example, the optical device 3 has a disc shape. Theoptical device 3 is positioned so that the center axis of the opticaldevice 3 is decentered with respect to the illumination position 52 ofthe coherent light beam.

Each of the plurality of diffusion regions 19 has a substantiallytrapezoidal shape and is arranged on the incident surface of the opticaldevice 3 along the circumference passing through the illuminationposition 52 of the coherent light beam without leaving a gap.

The driving unit 51 is, for example, a rotary motor, and is configuredso as to continuously rotate the optical device 3 around a central axisthereof. When the optical device 3 is rotated by the driving unit 51,each of the plurality of diffusion regions 19 held by the optical device3 sequentially passes through the illumination position 52 of thecoherent light beam. When viewed from the stationary system of theoptical device 3, the illumination position 52 of the coherent lightbeam sequentially scans the plurality of diffusion regions 19 held bythe optical device 3.

Incidentally, as mentioned in the section of the technical problem, in aconfiguration in which coherent light beam is scanned by using theoptical scanning unit including a galvanometer mirror, a MEMS mirror, orthe like, depending on the light source, the beam diameter of thecoherent light beam may be larger than the galvanometer mirror, and insome cases there is a possibility that the coherent light beam isnarrowed down in order to irradiate the galvanometer mirror. However, ifthe coherent light beam is focused down, there is a possibility that theenergy density is increased and the mirror may be affected by damage orthe like, and as a result, the light output may be inevitably reduced.Also, depending on the light source, if the coherent light beam isexcessively narrowed, the spread of the beam at the narrowed end (thatis, at the tip of the galvanometer mirror) becomes large, which maydegrade the incidence of light. In order to improve this, it isnecessary to enlarge the device. It is also conceivable to increase thesize of the galvanometer mirror without limiting the coherent lightbeam, but in this case, the whole device becomes large and expensive. Inaddition, it is difficult to make the entire device larger in size dueto the balance of placement. Also, since the structure of thegalvanometer mirror and the MEMS mirror is complicated, it may becomeunstable depending on the situation.

On the other hand, in the present embodiment, as described above,coherent light beam can be scanned on the optical device 3 without usingthe optical scanning unit including the galvanometer mirror, the MEMSmirror, or the like. Therefore, even when the beam diameter of thecoherent light beam emitted from the coherent light source is relativelylarge, there is no need to narrow the coherent light beam or enlarge theentire device. Further, in the present embodiment, since the simplestructure of rotating the optical device 3 by the rotary motor isadopted, as compared with the optical scanning unit including thegalvanometer mirror, the MEMS mirror or the like, the operation isunlikely to become unstable depending on the situation.

The driving unit 51 repeats the operation of rotating the optical device3 at a constant period, for example, and in synchronization with thisperiod, each of the plurality of diffusion regions 19 held by theoptical device 3 repeatedly passes through the illumination position 52of the coherent light beam in order.

FIGS. 36A and 36B are views showing how the plurality of diffusionregions 19 held by the optical device 3 sequentially reach theillumination position 52 of the coherent light beam.

As shown in FIGS. 36A and 36B, each of the plurality of diffusionregions 19 held by the optical device 3 diffuses the incident coherentlight beam and illuminates the corresponding partial region 10 a in thepredetermined illumination area 10. At least a part of the partialregion 10 a illuminated by each diffusion region 19 is different foreach diffusion region 19. That is, the partial regions 10 a illuminatedby different diffusion regions 19 are at least partially different.

Specifically, for example, each of the plurality of diffusion regions 19can be configured using a hologram recording medium in which a differentinterference fringe pattern is formed. The coherent light beam incidenton each diffusion region 19 is diffracted by the interference fringepattern formed in the diffusion region 19 to illuminate thecorresponding partial region 10 a in the predetermined illumination area10. By adjusting the interference fringe pattern variously, it ispossible to change the traveling direction of the coherent light beamdiffracted or diffused by each diffusion region 19.

In this manner, the coherent light beam incident on each point in eachdiffusion region 19 illuminates the corresponding partial region 10 a inthe predetermined illumination area 10. In addition, as a driving device14 continuously rotates the optical device 3 in the rotation direction,the incident position and the incident angle of the coherent light beamincident on each diffusion region 19 are changed with the lapse of time.The coherent light beam incident into one diffusion region 19illuminates the common partial region 10 a even if the coherent lightbeam is incident on any position in the diffusion region 19. That is,this means that the incident angle of the coherent light beam L incidenton each point of the partial region 10 a changes with the lapse of time.This change in the incident angle is a speed that cannot be resolved bythe human eye, and as a result, the scattering pattern of the coherentlight beam having no correlation is multiplexed and observed in thehuman eye. Therefore, the speckle generated corresponding to eachscattering pattern is overlapped and averaged, and is observed by theobserver. As a result, in the partial region 10 a, speckle becomes lessconspicuous. Since the incident position and incident angle of thecoherent light beam incident on each diffusion region 19 are changedwith the lapse of time, the coherent light beam diffracted at each pointin each diffusion region 19 has different wave fronts, and since thesediffracted coherent light beams are individually superimposed on thepartial region 10 a, a uniform illuminance distribution in which thespeckle is inconspicuous can be obtained in the partial region 10 a.

FIGS. 36A and 36B shows an example in which each diffusion region 19illuminates different partial regions 10 a in the predetermined area 10.However, a part of the partial region 10 a may overlap the adjacentpartial region 10 a. Further, the size of the partial region 10 a may bedifferent for each diffusion region 19. Furthermore, it is unnecessarythat the corresponding partial region 10 a is arranged in theillumination area 10 according to the arrangement order of the diffusionregion 19. That is, the arrangement order of the diffusion region 19 inthe optical device 3 and the arrangement order of the correspondingpartial region 10 a in the illumination area 10 are not necessarilycoincident.

Next, the structure of the hologram recording medium in the diffusionregion 19 will be described in detail.

The hologram recording medium can be manufactured by using, for example,scattered light from a real scattering plate as object light. Morespecifically, when the hologram photosensitive material which is thebase of the hologram recording medium is illuminated with referencelight and object light made of coherent light beam having coherency witheach other, an interference fringe pattern due to interference of theselight beams is formed on the hologram photosensitive material, and thehologram recording medium is manufactured. A laser beam which iscoherent light beam is used as reference light, and scattered light ofan isotropic scattering plate on which incidence of light can beperformed at low cost, for example, is used as object light.

By illuminating the hologram recording medium with coherent light beamfrom the focal position of the reference light used for manufacturingthe hologram recording medium, a reproduced image of the scatteringplate is generated at the arrangement position of the scattering platewhich is the source of the object light used in manufacturing thehologram recording medium. When the scattering plate which is the sourceof the object light used for manufacturing the hologram recording mediumhas uniform surface scattering, a reproduced image of the scatteringplate obtained by the hologram recording medium is also a uniform planeillumination, and a region where the reproduced image of this scatteringplate is generated is the partial region 10 a.

In the present embodiment, illumination control that illuminates only apart of the predetermined illumination area 10 can be performed usingthe plurality of diffusion regions 19 held by the optical device 3. Inorder to perform such illumination control using the hologram recordingmedium, the interference fringe pattern formed in each diffusion region19 becomes complicated. Instead of using actual object light andreference light for forming such a complicated interference fringepattern, the interference fringe pattern can be designed using acomputer based on the scheduled wavelength and incident direction of thereconstruction illumination light and the shape and position of theimage to be reproduced. The hologram recording medium thus obtained isalso called a computer generated hologram (CGH). In addition, a Fouriertransform hologram having the same diffusion angle characteristic ateach point on each diffusion region 19 may be formed by computersynthesis. Further, an optical member such as a lens may be provided onthe rear side of the optical axis of the predetermined illumination area10 to set the size and position of the actual illumination area.

One advantage of using the hologram recording medium as each of theplurality of diffusion regions 19 held by the optical device 3 is thatthe optical energy density of the coherent light beam can be reduced bydiffusion. Another advantage is that since the hologram recording mediumcan be used as a directivity surface light source, compared to theconventional lamp light source (point light source), it is possible toreduce the luminance on a light source surface necessary for achievingthe same illuminance distribution. This can contribute to improving thesafety of the coherent light beam, and even if the coherent light beamhaving passed through the predetermined illumination area 10 is vieweddirectly with a human eye, there is less possibility of adverselyaffecting the human eye as compared with the case of looking directly ata single point light source.

In FIG. 34, the example in which the coherent light beam is reflectedand diffused by the diffusion region 19 has been shown, but thediffusion region 19 may diffuse the coherent light beam in a transmittedmanner. For example, when a hologram recording medium is used as thediffusion region 19, the hologram recording medium may be a reflectiontype or a transmission type. Generally, the reflection type hologramrecording medium (hereinafter, reflection type holo) has high wavelengthselectivity as compared with the transmission type hologram recordingmedium (hereinafter, transmission type holo). That is, even when theinterference fringe pattern corresponding to different wavelengths islaminated the reflection type holo can diffract coherent light beam of adesired wavelength only in a desired layer. Also, the reflection typeholo is superior in that it is easy to remove the influence of zeroorder light. On the other hand, the transmission type holo has a widediffractable spectrum and a wide tolerance of the coherent light source4. However, when the interference fringe pattern corresponding todifferent wavelengths is laminated, coherent light beam of a desiredwavelength is diffracted even in a layer other than the desired layer.Therefore, in general, it is difficult to form a transmission type holowith a laminated structure.

As a specific form of the hologram recording medium, a volume hologramrecording medium using a photopolymer may be used, and a volumetrichologram recording medium of a type that performs recording using aphotosensitive medium containing a silver salt material may be used.Alternatively, a relief type (emboss type) hologram recording medium maybe used.

In the present embodiment, the driving device 14 sequentially makes theplurality of diffusion regions 19 held by the optical device 3 reach theillumination position 52 of the coherent light beam, and the timingcontrol unit 5 is configured to control the timing of the coherent lightbeam in synchronization with the timing at which each diffusion region19 reaches the illumination position 52.

It is possible to selectively illuminate an arbitrary area in thepredetermined illumination area 10 by controlling whether or not eachdiffusion region 19 is irradiated with the coherent light beam, by thetiming control unit 5. At this time, each partial region 10 a includedin the selected region is sequentially illuminated by coherent lightbeam at a speed as if illuminated simultaneously by the human eye.

Next, the operation of the present embodiment will be described bytaking as an example a case where the illumination device 1 is used as aheadlamp of a car.

As shown in FIG. 46, when there are no cars traveling in the front oroncoming cars in the predetermined illumination area 10, the timingcontrol unit 5 controls the timing of the coherent light beam so as toilluminate a region conforming to a high beam (also referred to as atraveling headlamp) standard (in the illustrated example, the entireregion of the predetermined illumination area 10).

Specifically, for example, coherent light beam is emitted from thecoherent light source 4 toward the illumination position 52, the opticaldevice 3 is continuously rotated by the driving unit 51, and each of theplurality of diffusion regions 19 held by the optical device 3sequentially passes through the illumination position 52 of the coherentlight beam.

At this time, the timing control unit 5 controls the timing of thecoherent light beam so that the all the diffusion regions 19 held by theoptical device 3 is irradiated with coherent light beam. As a result, asshown in FIG. 46, the entire region of the predetermined illuminationarea 10 is illuminated, and a pedestrian 59 etc. walking in the frontcan be visually recognized.

On the other hand, as shown in FIG. 47, when there is a car 60 travelingin the front or an oncoming car in the predetermined illumination area10, the timing control unit 5 controls the timing of the coherent lightbeam so as to illuminate a region conforming to a low beam (alsoreferred to as a passing headlamp) standard (for example, the regionbelow the horizontal plane among the predetermined illumination area10).

Specifically, for example, coherent light beam is emitted from thecoherent light source 4 toward the illumination position 52, the opticaldevice 3 is continuously rotated by the driving unit 51, and each of theplurality of diffusion regions 19 held by the optical device 3sequentially passes through the illumination position 52 of the coherentlight beam.

At this time, the timing control unit 5 identifies the partial region 10a corresponding to the region conforming to the low beam standard amongthe plurality of partial regions 10 a in the predetermined illuminationarea 10, and controls the timing of coherent light beam so that thediffusion region 19 corresponding to the identified partial region 10 ais irradiated with coherent light beam, but the other diffusion region19 is not irradiated with coherent light beam. As a result, as shown inFIG. 47, a region that meets the low beam standard in the predeterminedillumination area 10 is illuminated, and the other region in thepredetermined illumination area 10 is non-illuminated. Accordingly, itis possible to prevent the coherent light beam from dazzling the car 60traveling ahead and the driver of the oncoming vehicle.

According to the present embodiment as described above, the opticaldevice 3 holds the plurality of diffusion regions 19, and each diffusionregion 19 illuminates the corresponding partial region 10 a in thepredetermined illumination area 10. The driving unit 51 moves theoptical device 3 such that each of the plurality of diffusion regions 19sequentially passes through the illumination position 52 of the coherentlight beam. Therefore, when the timing of the coherent light beam is notcontrolled, the coherent light beam is diffused in all the diffusionregions 19 held by the optical device 3 so that the entire region of thepredetermined illumination area 10 can be illuminated as a whole.

Here, according to the present embodiment, coherent light beam can bediffused by sequentially irradiating the plurality of diffusion regions19 that demonstrate different partial regions with coherent light beamwithout using optical scanning unit including a galvanometer mirror, aMEMS mirror or the like. Therefore, even when the beam diameter of thecoherent light beam emitted from the coherent light source 4 isrelatively large, it is unnecessary to narrow down the coherent lightbeam or enlarge the entire device.

Further, according to the present embodiment, since it is possible toadopt a simple structure of rotating the optical device 3 by the rotarymotor as a structure for scanning the illumination position 52 of thecoherent light beam on the optical device 3, the operation is unlikelyto become unstable depending on the situation as compared with theoptical scanning unit including the galvanometer mirror, the MEMS mirroror the like.

Further, according to the present embodiment, the illumination position52 of the coherent light beam is scanned in each diffusion region 19,and since the coherent light beam incident on each point in eachdiffusion region 19 illuminates the entire region of the correspondingpartial region 10 a, the incident angle of the coherent light beam ineach partial region 10 a in the predetermined illumination area 10changes with the lapse of time, so that it is possible to make specklein each partial region 10 a inconspicuous.

Furthermore, according to the present embodiment, it is possible toselectively illuminate an arbitrary area in the predeterminedillumination area 10 by controlling whether or not each diffusion region19 is irradiated with the coherent light beam, by the timing controlunit 5. Thus, for example, when the illumination device 1 is used as aheadlamp of a car, it is possible to easily switch between a regionconforming to a high beam standard in the predetermined illuminationarea 10 and a region conforming to a low beam standard, and when thereis a car 60 traveling in the front or an oncoming car in thepredetermined illumination area 10, it is possible to prevent thecoherent light beam from dazzling the vehicle 60 traveling ahead and thedriver of the oncoming vehicle.

In the present embodiment, the timing control unit 5 is not alwaysindispensable. In the case where it is sufficient to illuminate theentire region of the predetermined illumination area 10 using coherentlight beam, such as when the illumination device 1 is used as a highbeam dedicated headlamp (running headlamp), the timing control unit 5may be omitted.

It is to be noted that various modifications can be made to theabove-described embodiment. Hereinafter, modifications will be describedwith reference to the drawings. In the following description and thedrawings used in the following description, the same reference numeralsas those used for the corresponding parts in the above-describedembodiments are used for parts that can be configured similarly to theabove-described embodiment, and overlapping explanation will be omitted.Further, when it is obvious that the operation and effect obtained inthe above-described embodiment can be obtained also in the modifiedexample, the explanation may be omitted.

Tenth Embodiment

FIG. 37 is a view showing a schematic configuration of an illuminationdevice according to the tenth embodiment of the present invention.

As shown in FIG. 37, in the tenth embodiment, the optical device 3 has acylindrical shape, and the outer peripheral surface of the opticaldevice 3 is an incident surface on which the coherent light beam isincident.

Each of the plurality of diffusion regions 19 has an elongated shapeextending in a direction parallel to the axial direction of the opticaldevice 3, and is arranged along the circumferential direction on theincident surface of the optical device 3, that is, on the outerperipheral surface.

The driving unit 51 is, for example, a rotary motor, and is configuredso as to continuously rotate the optical device 3 around a central axisthereof. When the optical device 3 is rotated by the driving unit 51,each of the plurality of diffusion regions 19 held by the optical device3 sequentially passes through the illumination position 52 of thecoherent light beam.

According to the tenth embodiment like this, in addition to obtainingthe same operational effect as the ninth embodiment, the followingoperational effects can be obtained. That is, in the case of enlargingeach diffusion region 19 in the longitudinal direction to increase thesize, in the ninth embodiment, twice as much space is required to theright and left around the rotation axis of the optical device 3. On theother hand, in the tenth embodiment, only one space is required in adirection parallel to the rotation axis of the optical device 3, thatis, the size of the entire device can be made compact.

Eleventh Embodiment

FIG. 38 is a view showing a schematic configuration of an illuminationdevice according to the eleventh embodiment of the present invention.

As shown in FIG. 38, in the eleventh embodiment, the optical device 3has a pair of rotating rollers 3 a, 3 b rotatable about their respectiveaxes, and a belt-like portion 3 c looped around a pair of rotatingrollers 3 a, 3 b. In the illustrated example, the number of the rotatingrollers 3 a and 3 b is two, but may be three or more. The pair ofrotating rollers 3 a, 3 b are arranged in parallel to each other. Theouter peripheral surface of the belt-like portion 3 c is an incidentsurface on which the coherent light beam is incident.

Each of the plurality of diffusion regions 19 has an elongated shapeextending in a direction parallel to the axial direction of the rotatingrollers 3 a and 3 b, and on the outer surface of the belt-like portion 3c, is arranged along the longitudinal direction of the belt-like portion3 c, that is, along the looped direction of the belt-like portion 3 c.

The driving unit 51 is, for example, a rotary motor, and is configuredso as to continuously rotate at least one rotating roller 3 a about anaxis thereof. As the at least one rotating roller 3 a is rotated by thedriving unit 51, the belt-like portion 3 c is moved in the loopingdirection, and each of the plurality of diffusion regions 19 arranged onthe belt-like portion 3 c passes through the illumination position 52 ofthe coherent light beam in order.

According to the eleventh embodiment like this, in addition to obtainingthe same operational effect as the tenth embodiment, the followingoperational effects can be obtained. That is, in the eleventhembodiment, as compared with the tenth embodiment, since the thicknessof the optical device 3 is thin, it is easy to install the opticaldevice 3 in a narrow space such as under a bonnet of a car.

Twelfth Embodiment

FIG. 39 is a view showing a schematic configuration of an illuminationdevice according to a twelfth embodiment of the present invention. FIG.40 is a plan view of the diffusion unit in the illumination device inFIG. 39.

As shown in FIGS. 39 and 40, in the twelfth embodiment, each of theplurality of diffusion regions 19 has an elongated shape extending in adirection perpendicular to the moving direction of the optical device 3,and in the illustrated example, a radial direction perpendicular to therotation direction.

In addition, the coherent light source 4 has a laser array arranged in adirection perpendicular to the moving direction of the optical device 3,and in the illustrated example, in a radial direction perpendicular tothe rotation direction. Since the laser array is arranged in parallelwith the longitudinal direction of the diffusion region 19, a pluralityof coherent light beams emitted from the laser array are simultaneouslyincident on the same single diffusion region 19.

According to the twelfth embodiment, the light emission intensity of thecoherent light beam can be increased.

Thirteenth Embodiment

FIG. 41 is a view showing a schematic configuration of an illuminationdevice according to the thirteenth embodiment of the present invention.

As shown in FIG. 41, in the thirteenth embodiment, the plurality ofcoherent light sources 4 r, 4 g, and 4 b that emit coherent light beamshaving different emission wavelength ranges are provided, and theoptical device 3 is provided with a plurality of diffusion regions 19 r,19 g, and 19 b corresponding to each of the coherent light beams havingdifferent emission wavelength ranges. In each partial region 10 a in thepredetermined illumination area 10, coherent light beams diffused in therespective diffusion regions 19 r, 19 g, and 19 b and having differentemission wavelength ranges are overlapped and illuminated.

According to the thirteenth embodiment, for example, when red coherentlight beam, green coherent light beam and blue coherent light beam areused as coherent light beam, in each partial region 10 a in thepredetermined illumination area 10, these three colors are mixed and canbe illuminated with white light.

In the example shown in FIG. 41, the plurality of diffusion regions 19r, 19 g, and 19 b corresponding to coherent light beams having differentemission wavelength ranges are held by the common optical device 3;however, the present invention is not limited to thereto. The pluralityof diffusion regions 19 r, 19 g, and 19 b corresponding to coherentlight beams having different emission wavelength ranges are held inseparate optical devices 3, respectively, so that each optical device 3is rotated about an axis thereof. In this case, since the energy of thecoherent light beam is dispersed, the temperature rise of each opticaldevice 3 can be suppressed. On the other hand, when the plurality ofdiffusion regions 19 r, 19 g, and 19 b corresponding to each of thecoherent light beams having different light wavelength regions are heldby the common optical device 3, the size of the entire device becomescompact.

Fourteenth Embodiment

FIG. 43 is a view showing a schematic configuration of the illuminationdevice according to the fourteenth embodiment of the present invention.

As shown in FIG. 43, in the fourteenth embodiment, there is provided anobject detection unit 21 for detecting an object existing in thepredetermined illumination area 10. The object detection unit 21 isconnected to the timing control unit 5.

More specifically, the object detection unit 21 includes an imagingdevice 53 that images an inside of the predetermined illumination area10, and an image processing unit 54 that performs image processing onthe imaging result of the imaging device 53 and recognizes an object inthe predetermined illumination area 10.

As the imaging device 53, for example, a commercially available imagingdevice equipped with a CCD that converts light emitted or reflected froman object existing in the predetermined illumination area 10 to anelectrical signal can be used. The image processing unit 54 performsimage processing on the imaging result of the imaging device 53,determines whether or not an object exists in the predeterminedillumination area 10, and when it is determined that the object exists,the image processing unit 54 identifies the partial region 10 aoverlapping with at least a part of the object in the predeterminedillumination area 10.

The timing control unit 5 controls the timing of the coherent light beamso as to illuminate the object detected by the object detection unit 31.

More specifically, for example, the timing control unit 5 controls thetiming of coherent light beam so that the diffusion region 19corresponding to the partial region 10 a identified by the imageprocessing unit 31 is irradiated with coherent light beam, but the otherdiffusion region 19 is not irradiated with coherent light beam.

According to the fourteenth embodiment, for example, when theillumination device 1 is used as a headlamp of a car, the driver whodrives the car can automatically illuminate the object in thepredetermined illumination area 10 without manually selecting the areato be illuminated in the predetermined illumination area 10, so that thesafety of driving can be improved.

Fifteenth Embodiment

FIG. 44 is a view showing a schematic configuration of the illuminationdevice according to the fifteenth embodiment of the present invention.

As shown in FIG. 44, in the fifteenth embodiment, the object detectionunit 21 includes a position information acquiring unit 55 that acquiresposition information of a car in which the illumination device 1 isdisposed, a storage unit 56 that stores the position information of theobject, and an information processing unit 57 that recognizes the objectin the predetermined illumination area 10 based on the positioninformation of the car acquired by the position information acquiringunit 55 and the position information of the object stored in the storageunit 56.

As the position information acquiring unit 55, for example, acommercially available GPS receiver that acquires position informationof the car using a global positioning system (GPS) can be used. Thestorage unit 56 may store the map data in a wide area in advance or mayread and store only the map data around the current position of the carfrom an external database.

Based on the position information of the car acquired by the positioninformation acquiring unit 55 and the position information of the objectstored in the storage unit 56, the information processing unit 57determines whether or not an object exists in the predeterminedillumination area 10, and when it is determined that the object exists,the information processing unit 57 identifies the partial region 10 aoverlapping with at least a part of the object in the predeterminedillumination area 10.

According to the fifteenth embodiment, even when the imaging device 53according to the fourteenth embodiment cannot clearly capture the insideof the predetermined illumination area 10 due to bad weather or thelike, if there exists an object stored in the storage unit 56, theobject can be appropriately recognized and illuminated.

Sixteenth Embodiment

FIG. 45 is a view showing a schematic configuration of the illuminationdevice according to the sixteenth embodiment of the present invention.

As shown in FIG. 45, in the sixteenth embodiment, a handle rotationdetection unit 58 is provided for detecting the rotation of a handle ofa car in which the illumination device 1 is installed. The handlerotation detection unit 58 is connected to the light emission timingcontrol unit 5.

The light emission timing control unit 5 controls the light emissiontiming of the coherent light beam based on the rotation of the handledetected by the handle rotation detection unit 58.

Specifically, for example, in the case where the handle is rotated tothe left (or right), the light emission timing control unit 5 identifiesthe partial region 10 a corresponding to the front illumination regionand the partial region 10 a corresponding to the illumination regionadjacent on the left side (or the right side) with respect to the frontillumination region among the plurality of partial regions 10 a in thepredetermined illumination area 10, and controls the light emissiontiming of the coherent light beam so that the diffusion region 19corresponding to the specified partial region 10 a is irradiated withthe coherent light beam, but the other diffusion region 19 is notirradiated with the coherent light beam. Accordingly, the center of thearea to be illuminated is moved in the direction in which the handle isrotated, and the visibility in the traveling direction of the car isimproved.

Seventeenth Embodiment

FIG. 48 is a view showing a schematic configuration of the illuminationdevice 1 according to the seventeenth embodiment of the presentinvention.

As shown in FIG. 48, in the illumination device 1 according to thepresent embodiment includes the coherent light source 4 that emitscoherent light beam, the optical device 3 that diffuses the coherentlight beam and illuminating the predetermined illumination area 10, anda scanning unit 6 that causes coherent light beam from the coherentlight source 4 to scan on the optical device 3.

As the coherent light source 4, for example, a semiconductor laser lightsource can be used. In order to increase the light emission intensity,the coherent light source 4 may be configured to collect the coherentlight beam emitted from the plurality of laser light sources with thefiber and emit the light.

The scanning unit 6 changes the traveling direction of the coherentlight beam from the coherent light source 4 with the lapse of time sothat the traveling direction of the coherent light beam does not becomeconstant. As a result, the coherent light beam emitted from the scanningunit 6 is scanned on the incident surface of the optical device 3.

For example, as shown in FIG. 49, the scanning unit 6 has a reflectivedevice 63 that can rotate around two rotating axes 61 and 62 extendingin mutually intersecting directions. The coherent light beam from thecoherent light source 4 incident on the reflecting surface of thereflective device 63 is reflected at an angle corresponding to aninclination angle of the reflecting surface and travels toward anincident surface of the optical device 3. By rotating the reflectivedevice 63 around the two rotation axes 61 and 62, the coherent lightbeam is scanned on the incident surface of the optical device 3two-dimensionally. Since the reflective device 63 repeats the operationof rotating around the two rotation axes 61 and 62 at a constant period,for example, the coherent light beam is repeatedly two-dimensionallyscanned on the incident surface of the optical device 3 insynchronization with this period.

The optical device 3 has an incident surface on which coherent lightbeam is incident, and diffuses the coherent light beam incident on theincident surface to illuminate the predetermined illumination area 10.More specifically, the coherent light beam diffused by the opticaldevice 3 passes through the predetermined illumination area 10 and thenilluminates the actual illumination area.

Here, the predetermined illumination area 10 is the illumination area ofthe near field illuminated by the optical device 3. The illuminationarea of the far field is often expressed as a diffusion angledistribution in the angular space rather than the actual size of theillumination area. In the present specification, the term “predeterminedarea” includes a diffusion angle area in the angular space in additionto the actual illumination zone (illumination area). Therefore, theillumination area illuminated by the illumination device 1 in FIG. 48can be a much wider area than the illumination area 10 of near fieldshown in FIG. 48.

FIG. 50 is a view showing how the coherent light beam diffused by theoptical device 3 enters the predetermined illumination area 10. Theoptical device 3 diffuses the incident coherent light beam andilluminates the entire region of the predetermined illumination area 10as a whole.

As shown in FIG. 50, the optical device 3 has the plurality of elementdiffusion regions 19. Each element diffusion region 19 diffuses theincident coherent light beam and illuminates the corresponding partialregion 10 a in the predetermined illumination area 10. At least a partof the partial region 10 a differs for each element diffusion region 19.

Specifically, for example, the optical device 3 can be configured usingthe hologram recording medium. In the following description, thehologram recording medium in the optical device 3 may be described withthe same reference numeral as that of the optical device 3. The coherentlight beam incident on the hologram recording medium 13 is diffused toilluminate the entire region of the predetermined illumination area 10as a whole.

As shown in FIG. 50, the hologram recording medium 13 has a plurality ofelement hologram areas. In the following description, the elementhologram area may be described with the same reference numeral as thatof the element diffusion region 19. Each of the plurality of elementhologram areas 13 a illuminates the corresponding partial region 10 a inthe predetermined illumination area 10 by diffusing the incidentcoherent light beam. At least a part of the partial region 10 ailluminated by each element hologram area 13 a is different for eachelement hologram area 13 a. That is, the partial regions 10 ailluminated by the different element hologram areas 13 a are at leastpartially different from each other.

In each element hologram area 13 a, an interference fringe pattern isformed. Therefore, the coherent light beam incident on each elementhologram area 13 a is diffracted by the interference fringe pattern toilluminate the corresponding partial region 10 a in the predeterminedillumination area 10. By adjusting the interference fringe patternvariously, it is possible to change the traveling direction of coherentlight beam diffracted or diffused by each element hologram area 13 a.

In this manner, the coherent light beam incident on each point in eachelement hologram area 13 a illuminates the corresponding partial region10 a in the predetermined illumination area 10. In addition, thescanning unit 6 scans each of the element hologram areas 13 a withcoherent light beam, thereby changing the incidence position and theincident angle of coherent light beam incident on each of the elementhologram areas 13 a over time. The coherent light beam incident into oneelement hologram area 13 a illuminates the common partial region 10 aeven if the coherent light beam is incident on any position in theelement hologram area 13 a. That is, this means that the incident angleof the coherent light beam incident on each point of the partial region10 a changes with the lapse of time. This change in the incident angleis a speed that cannot be resolved by the human eye, and as a result,the scattering pattern of the coherent light beam having no correlationis multiplexed and observed in the human eye. Therefore, the specklegenerated corresponding to each scattering pattern is overlapped andaveraged, and is observed by the observer. As a result, in the partialregion 10 a, speckle becomes less conspicuous. Since the incidentposition and incident angle of the coherent light beam incident on eachelement hologram area 13 a are changed with the lapse of time, thecoherent light beam diffracted at each point in each element hologramarea 13 a has different wave fronts, and since these diffracted coherentlight beams are individually superimposed on the partial region 10 a, auniform illuminance distribution in which the speckle is inconspicuouscan be obtained in the partial region 10 a.

FIG. 50 shows an example in which each element hologram area 13 ailluminates different partial regions 10 a in the predeterminedillumination area 10. However, a part of the partial region 10 a mayoverlap the adjacent partial region 10 a. In addition, the size of thepartial region 10 a may be different for the elementary hologram area 13a. Furthermore, it is unnecessary that the corresponding partial region10 a is arranged in the illumination area 10 according to thearrangement order of the element hologram area 13 a. That is, thearrangement order of the element hologram area 13 a in the hologramrecording medium 13 and the arrangement order of the correspondingpartial region 10 a in the predetermined illumination area 10 are notnecessarily coincident.

In the present embodiment, the scanning unit 6 periodically scans thecoherent light beam from the coherent light source 4 on the incidentsurface of the optical device 3. At this time, each of the partialregions 10 a in the predetermined illumination area 10 is sequentiallyilluminated by the coherent light beam diffused in the correspondingelement diffusion region 19 at a speed as if illuminated simultaneouslyby the human eye.

Returning to FIG. 48, the illumination device 1 according to the presentembodiment includes an operation monitoring unit 64 that monitors theoperation of the scanning unit 6, and an auxiliary illumination unit 65that illuminates the predetermined illumination area 10 when anoperation abnormality of the scanning unit 6 is detected by theoperation monitoring unit 64.

Specifically, for example, the operation monitoring unit 64 isconfigured to monitor the change in a current value flowing through amotor for rotating the reflective device 63 of the scanning unit 6around the two rotating axes 61 and 62, and when the current valuedeviates from the predetermined range, to determine that an abnormalityhas occurred in the operation of the scanning unit 6 (failed).

In the present embodiment, the auxiliary illumination unit 65 includesan auxiliary mirror 66 disposed in an optical path between the coherentlight source 4 and the scanning unit 6 when an operation abnormality ofthe scanning unit 6 is detected by the operation monitoring unit 64, andan auxiliary diffusion device 67 that diffuses coherent light beam andilluminates the predetermined illumination area 10.

The auxiliary mirror 66 is usually positioned outside the optical pathbetween the coherent light source 4 and the scanning unit 6. A drivingunit (for example, a motor) (not shown) is provided on the auxiliarymirror 66. On the basis of the abnormality detection signal of thescanning unit 6 by the operation monitoring unit 64, the driving unit ofthe auxiliary mirror 66 is adapted to insert the auxiliary mirror 66into the optical path between the coherent light source 4 and thescanning unit 6 as shown by the broken line in FIG. 48 and shown in FIG.51.

The reflecting surface of the auxiliary mirror 66 is inclined in such adirection as to reflect the coherent light beam from the coherent lightsource 4 toward the incident surface of the auxiliary diffusion device67.

The auxiliary diffusion device 67 has an incident surface on whichcoherent light beam is incident, and diffuses the coherent light beamincident on the incident surface to illuminate the predeterminedillumination area 10. In the illustrated example, the auxiliarydiffusion device 67 diffuses the incident coherent light beam toilluminate the entire region of the predetermined illumination are 10,but the present invention is not limited thereto. For example, theauxiliary diffusion device 67 may be adapted to illuminate the partialregion 10 a including at least the front direction in the predeterminedillumination area 10.

Specifically, for example, the auxiliary diffusion device 67 can beconfigured using a hologram recording medium in which an interferencefringe pattern is formed. In this case, the coherent light beam incidenton the auxiliary diffusion device 67 is diffracted by the interferencefringe pattern to illuminate the predetermined illumination area 10.

Next, the structure of the hologram recording medium in the opticaldevice 3 and the auxiliary diffusion device 67 will be described indetail.

The hologram recording medium can be manufactured by using, for example,scattered light from a real scattering plate as object light. Morespecifically, when the hologram photosensitive material which is thebase of the hologram recording medium is illuminated with referencelight and object light made of coherent light beam having coherency witheach other, an interference fringe pattern due to interference of theselight beams is formed on the hologram photosensitive material, and thehologram recording medium 13 is manufactured. A laser beam which iscoherent light beam is used as reference light, and scattered light ofan isotropic scattering plate on which incidence of light can beperformed at low cost, for example, is used as object light.

By illuminating the hologram recording medium with coherent light beamfrom the focal position of the reference light used for manufacturingthe hologram recording medium, a reproduced image of the scatteringplate is generated at the arrangement position of the scattering platewhich is the source of the object light used in manufacturing thehologram recording medium. When the scattering plate which is the sourceof the object light used for manufacturing the hologram recording mediumhas uniform surface scattering, a reproduced image of the scatteringplate obtained by the hologram recording medium is also a uniform planeillumination, and a region where the reproduced image of this scatteringplate is generated is the predetermined illumination area 10.

In the present embodiment, illumination control that illuminates onlypart of the virtual illumination area can be performed using the opticaldevice 3. In order to perform such illumination control using thehologram recording medium 13, the interference fringe pattern formed ineach element hologram area 13 a becomes complicated. Instead of usingactual object light and reference light for forming such a complicatedinterference fringe pattern, the interference fringe pattern can bedesigned using a computer based on the scheduled wavelength and incidentdirection of the reconstruction illumination light and the shape andposition of the image to be reproduced. The hologram recording medium 13thus obtained is also called a computer generated hologram (CGH). Inaddition, a Fourier transform hologram having the same diffusion anglecharacteristic at each point on each element hologram area 13 a may beformed by computer synthesis. Further, the auxiliary diffusion device 67may include a computer generated hologram. Further, an optical membersuch as a lens may be provided on the rear side of the optical axis ofthe predetermined illumination area 10 to set the size and position ofthe actual illumination area.

One of the advantages of providing the hologram recording medium as theoptical device 3 and the auxiliary diffusion device 67 is that the lightenergy density of the coherent light beam can be reduced by diffusion.Another advantage is that since the hologram recording medium can beused as a directivity surface light source, compared to the conventionallamp light source (point light source), it is possible to reduce theluminance on a light source surface necessary for achieving the sameilluminance distribution. This can contribute to improving the safety ofthe coherent light beam, and even if the coherent light beam havingpassed through the predetermined illumination area 10 is viewed directlywith a human eye, there is less possibility of adversely affecting thehuman eye as compared with the case of looking directly at a singlepoint light source.

FIG. 48 shows an example in which the coherent light beam is diffusedthrough the optical device 3 and the auxiliary diffusion device 67.However, the optical device 3 and the auxiliary diffusion device 67 maydiffuse and reflect coherent light beam. For example, when the hologramrecording medium is used as the optical device 3 and the auxiliarydiffusion device 67, the hologram recording medium may be a reflectiontype or a transmission type. Generally, the reflection type hologramrecording medium (hereinafter, reflection type holo) has high wavelengthselectivity as compared with the transmission type hologram recordingmedium (hereinafter, transmission type holo). That is, even when theinterference fringe pattern corresponding to different wavelengths islaminated the reflection type holo can diffract coherent light beam of adesired wavelength only in a desired layer. Also, the reflection typeholo is superior in that it is easy to remove the influence of zeroorder light. On the other hand, the transmission type holo has a widediffractable spectrum and a wide tolerance of the coherent light source4; however, when the interference fringe pattern corresponding todifferent wavelengths is laminated, coherent light beam of a desiredwavelength is diffracted even in a layer other than the desired layer.Therefore, in general, it is difficult to form a transmission type holowith a laminated structure.

As a specific form of the hologram recording medium, a volume hologramrecording medium using a photopolymer may be used, and a volumetrichologram recording medium of a type that performs recording using aphotosensitive medium containing a silver salt material may be used.Alternatively, a relief type (emboss type) hologram recording medium maybe used.

Next, the operation of the present embodiment will be described bytaking as an example a case where the illumination device 1 is used as aheadlamp of a moving body. In this specification, the moving body meansa moving device capable of moving in a three-dimensional space, inparticular, a vehicle. The moving body may be, for example, a cartraveling on the ground, more particularly an automobile, or a shiptraveling on the sea, a submarine moving in the sea, an airplane movingin the air, or the like.

When illuminating the predetermined illumination area 10, coherent lightbeam is emitted from the coherent light source 4 toward the scanningunit 6. The scanning unit 6 periodically scans the coherent light beamfrom the coherent light source 4 on the incident surface of the opticaldevice 3.

Coherent light beam incident on each element diffusion region 19 of theoptical device 3 illuminates the corresponding partial region 10 a inthe predetermined illumination area 10. At this time, each of thepartial regions 10 a in the predetermined illumination area 10 issequentially illuminated by the coherent light beam diffused in thecorresponding element diffusion region 19 at a speed as if illuminatedsimultaneously by the human eye. By scanning the element diffusionregions 19 of the optical device 3 with the coherent light beam by thescanning unit 6, all the partial regions 10 a in the predeterminedillumination area 10 are illuminated, that is, the entire region of thepredetermined illumination area 10 is illuminated.

Next, consider a case where an abnormality has occurred in the operationof the scanning unit 6 (failed).

As mentioned in the section of the technical problem, when coherentlight beam is incident on the failed scanning unit 6, the coherent lightbeam emitted from the scanning unit 6 is incident only on one elementdiffusion region 19 on the optical device 3, only a part of the partialregion 10 a in the predetermined illumination area 10 in front of themoving body is illuminated by the coherent light beam diffused in theelement diffusion region 19, so that there is a possibility of causingsafety problems. Specifically, for example, when only the partial region10 a at the end of the predetermined illumination area 10 is to beilluminated, visibility in the front direction cannot be secured.

On the other hand, in the present embodiment, the operation monitoringunit 64 monitors the change in the current value flowing through themotor that rotates the reflective device 63 of the scanning unit 6, andbased on the change in the current value, detects the operationabnormality of the scanning unit 6. The auxiliary illumination unit 65illuminates the predetermined illumination area 10 based on theabnormality detection signal of the scanning unit 6 by the operationmonitoring unit 64.

More specifically, when receiving the abnormality detection signal fromthe operation monitoring unit 64, the driving unit of the auxiliarymirror 66 inserts the auxiliary mirror 66 into the optical path betweenthe coherent light source 4 and the scanning unit 6 as shown by a brokenline in FIG. 48 and shown in FIG. 51. Thus, coherent light beam from thecoherent light source 4 is prevented from entering the failed scanningunit 6.

The auxiliary mirror 66 inserted in the optical path between thecoherent light source 4 and the scanning unit 6 reflects the coherentlight beam from the coherent light source 4 toward the incident surfaceof the auxiliary diffusion device 67.

The coherent light beam incident on the incident surface of theauxiliary diffusion device 67 is diffracted by the interference fringepattern of the auxiliary diffusion device 67 to illuminate thepredetermined illumination area 10. In the illustrated example, theentire region of the predetermined illumination area 10 is illuminated,but only the partial region 10 a, including the front direction, may beilluminated. Accordingly, the visibility in the front direction of themoving body can be secured.

As described above, according to the present embodiment, when anoperation abnormality of the scanning unit 6 is detected by theoperation monitoring unit 64, the predetermined illumination area 10 isilluminated by the auxiliary illumination unit 65. Specifically, forexample, based on the abnormality detection signal of the scanning unit6 by the operation monitoring unit 64, the auxiliary mirror 66 isdisposed in the optical path between the coherent light source 4 and thescanning unit 6. The coherent light beam from the coherent light source4 is reflected by the auxiliary mirror 66, and is incident on theauxiliary diffusion device 67. The coherent light beam diffused by theauxiliary diffusion device 67 illuminates the predetermined illuminationarea 10. Thereby, even when the scanning unit 6 fails, it is possible toensure the visibility in the front direction of the moving body, and itis possible to improve the safety of night driving.

It is to be noted that various modifications can be made to theabove-described embodiment. Hereinafter, modifications will be describedwith reference to the drawings. In the following description and thedrawings used in the following description, the same reference numeralsas those used for the corresponding parts in the above-describedembodiments are used for parts that can be configured similarly to theabove-described embodiment, and overlapping explanation will be omitted.Further, when it is obvious that the operation and effect obtained inthe above-described embodiment can be obtained also in the modifiedexample, the explanation may be omitted.

Eighteenth Embodiment

FIG. 52 is a view showing a schematic configuration of the illuminationdevice according to the eighteenth embodiment of the present invention.FIG. 53 is a view showing how coherent light beam is incident on theoptical device 3 by the auxiliary mirror 66.

As shown in FIGS. 52 and 53, in the eighteenth embodiment, the auxiliarydiffusion device 67 is omitted from the auxiliary illumination device20, and the auxiliary mirror 66 allows the coherent light beam from thecoherent light source 4 to be incident on the optical device 3.

In the illustrated example, on the element diffusion region 19corresponding to the partial region 10 a including the front directionin the predetermined illumination area 10 in the optical device 3, theauxiliary mirror 66 allows coherent light beam from the coherent lightsource 4 to be incident.

In the eighteenth embodiment, similar to the seventeenth embodiment, theoperation monitoring unit 64 monitors the change in the current valueflowing through the motor that rotates the reflective device 63 of thescanning unit 6, and based on the change in the current value, detectsthe operation abnormality of the scanning unit 6.

When receiving the abnormality detection signal from the operationmonitoring unit 64, the driving unit of the auxiliary mirror 66 insertsthe auxiliary mirror 66 into the optical path between the coherent lightsource 4 and the scanning unit 6 as shown by a broken line in FIG. 52and shown in FIG. 53. Thus, coherent light beam from the coherent lightsource 4 is prevented from entering the failed scanning unit 6.

The auxiliary mirror 66 inserted in the optical path between thecoherent light source 4 and the scanning unit 6 reflects the coherentlight beam from the coherent light source 4 toward the incident surfaceof the optical device 3.

The coherent light beam incident on the incident surface of the opticaldevice 3 is diffracted by the interference fringe pattern of the opticaldevice 3 to illuminate the predetermined illumination area 10. In theillustrated example, coherent light beam from the auxiliary mirror 66 isincident on the element diffusion region 19 corresponding to the partialregion 10 a including the front direction in the predeterminedillumination area 10 in the optical device 3. Therefore, the partialregion 10 a including the front direction in the predeterminedillumination area 10 is illuminated by the coherent light beam diffusedin the element diffusion region 19.

According to the eighteenth embodiment described above, when thescanning unit 6 fails, only the partial region 10 a at the end in frontof the moving body is prevented from being illuminated, and at leastvisibility of the moving body in the front direction can be secured.

Nineteenth Embodiment

FIG. 54 is a view showing a schematic configuration of the illuminationdevice according to the nineteenth embodiment of the present invention.

As shown in FIG. 54, in the nineteenth embodiment, the auxiliaryillumination device 20 has an auxiliary light source 68 different fromthe coherent light source 4. As the auxiliary light source 68, forexample, another light source previously provided in a moving body suchas a fog light can be used.

The auxiliary light source 68 is connected to the operation monitoringunit 64, and illuminates the predetermined region 30, as indicated bythe broken line in FIG. 54, based on the abnormality detection signal ofthe scanning unit 6 by the operation monitoring unit 64.

According to the nineteenth embodiment like this, even when the scanningunit 6 fails, it is possible to ensure the visibility in the frontdirection of the moving body, and it is possible to improve the safetyof night driving. In this case, it is preferable that the coherent lightsource 4 is connected to the operation monitoring unit 64, and the lightemission of the coherent light beam is stopped based on the abnormalitydetection signal of the scanning unit 6 by the operation monitoring unit64 from the viewpoint of suppressing energy consumption.

The specific form of the optical device 3 is not limited to the hologramrecording medium, and may be various diffusion members that can befinely divided into the plurality of element diffusion regions 19. Forexample, the optical device 3 may be configured using a lens array groupin which each element diffusion region 19 is a single lens array. Inthis case, a lens array is provided for each element diffusion region19, and the shape of each lens array is designed so that each lens arrayilluminates the corresponding partial region 10 a in a predeterminedangle area. At least a part of each partial region 10 a is different.Thus, the same operation and effect as in the case of constructing theoptical device 3 using the hologram recording medium can be obtained.

Further, in the above-described embodiment, coherent light beam in asingle emission wavelength range is used as the coherent light beam, butthe present invention is not limited thereto. By providing, as thecoherent light source 4, the plurality of laser light sources that emitcoherent light beams having different emission wavelength ranges, and byproviding the plurality of diffusion regions corresponding to each ofthe coherent light beams having different emission wavelength ranges inthe optical device 3 and the auxiliary diffusion device 67, in eachpartial region 10 a in the predetermined illumination area 10, coherentlight beam diffused in each diffusion region and having differentemission wavelength ranges may be superimposed and illuminated. Forexample, when red coherent light beam, green coherent light beam andblue coherent light beam are used as coherent light beam, in eachpartial region 10 a in the predetermined illumination area 10, thesethree colors are mixed and illuminated with white light.

Further, in the above-described embodiment, a case where the presentinvention is applied to the headlamp of the moving body has beenexemplified, but the object to which the present invention is applied isnot limited to the headlamp of the moving body. The present invention isapplicable to all illumination devices including a coherent lightsource, an optical scanning unit, and a diffusion element such as ahologram, regardless of whether the illumination device is used in amoving body or not.

An aspect of the present invention is not limited to each embodimentdescribed above, but includes various modifications that can beconceived by those skilled in the art, and the effects of the presentinvention are not limited to the contents described above. That is,various additions, modifications and partial deletions are possiblewithout departing from the conceptual idea and gist of the presentinvention derived from the contents defined in the claims and theirequivalents.

REFERENCE SIGNS LIST

-   1 Illumination device-   2 Irradiation device-   3 Optical device-   4 Laser light source-   5 Light emission timing control unit-   6 Light scanning device-   7 Light source unit-   01 Illumination zone-   11, 12 Rotation axis-   13 Reflective device-   14 Diffusion region part-   15 First area-   16 First diffusion region-   17 Second area-   18 Second diffusion region-   19 Element diffusion region-   21 Object detection unit-   22 Object-   23 Illumination area-   24 Event detection unit-   25 Optical shutter-   26 Beam diameter expansion member-   27 Collimating optical system-   30 Hologram recording medium-   31 Element hologram area-   32 Hologram area-   41 Liquid crystal cell-   42 Alignment film-   43 TN type liquid crystal material-   44 Polarization filter-   51 Driving unit-   52 Illumination position-   53 Imaging device-   54 Image processing unit-   55 Position information acquiring unit-   56 Storage unit-   57 Information processing unit-   58 Handle rotation detection unit

The invention claimed is:
 1. An illumination device comprising: acoherent light source that emits coherent light beam; an optical devicethat diffuses the coherent light beam; and a scanning unit that scansthe coherent light beam emitted by the coherent light source on theoptical device, wherein the optical device comprises a first diffusionregion that diffuses the coherent light beam scanned on the opticaldevice by the scanning unit to illuminate a first area provided on aground level, and a second diffusion region that diffuses the coherentlight beam scanned on the optical device by the scanning unit to displaypredetermined information in a second area provided on the ground level,wherein the predetermined information is a guidance information, andwherein a coherent light beam emitted from the second diffusion regionhas a shape of the guidance information, and wherein the seconddiffusion region displays the guidance information by projecting thecoherent light beam having the shape of the guidance information ontothe second area on the ground level.
 2. The illumination deviceaccording to claim 1, comprising a timing control unit that controls anincident timing of the coherent light beam on the optical device orcontrols an illumination timing in the first area and a display timingin the second area.
 3. An illumination device comprising: a coherentlight source that emits coherent light beam; an optical devicecomprising a first diffusion region that diffuses the coherent lightbeam to illuminate a first area provided on a ground level, and a seconddiffusion region that diffuses the coherent light beam to displaypredetermined information in a second area provided on the ground level;and a timing control unit that controls a light emission timing at whichthe coherent light source emits the coherent light so that the coherentlight illuminates the first diffusion region and the second diffusionregion, an incident timing at which the coherent light from the coherentlight source is incident on the first diffusion region and the seconddiffusion region, or an illumination timing at which the coherent lightdiffused by the optical device illuminates the first area and the secondarea, wherein the predetermined information is a guidance information,wherein a coherent light beam emitted from the second diffusion regionhas a shape of the guidance information, and wherein the seconddiffusion region displays the guidance information by projecting thecoherent light beam having the shape of the guidance information ontothe second area on the ground.
 4. The illumination device according toclaim 3, comprising a scanning unit that scans the coherent light beamemitted by the coherent light source on the optical device, wherein thefirst diffusion region diffuses coherent light beam from the scanningunit to illuminate the first area, and the second diffusion regiondiffuses the coherent light beam from the scanning unit to display thepredetermined information in the second area.
 5. The illumination deviceaccording to claim 2, comprising an event detection unit that detects anoccurrence of a specific event, wherein the timing control unit controlsthe scanning timing of the coherent light beam in at least one of thefirst diffusion region and the second diffusion region when it isdetected by the event detection unit that the specific event hasoccurred.
 6. The illumination device according to claim 4, comprising anevent detection unit that detects an occurrence of a specific event,wherein the timing control unit controls the scanning timing of thecoherent light beam in at least one of the first diffusion region andthe second diffusion region when it is detected by the event detectionunit that the specific event has occurred.
 7. The illumination deviceaccording to claim 1, wherein the guidance information comprises a routeguidance information of a moving body.
 8. The illumination deviceaccording to claim 3, wherein the guidance information comprises a routeguidance information of a moving body.
 9. The illumination deviceaccording to claim 7, wherein the route guidance information of themoving body comprises at least one of information indicating a travelingdirection of the moving body and information indicating a direction inwhich traveling of the moving body is prohibited.
 10. The illuminationdevice according to claim 8, wherein the route guidance information ofthe moving body comprises at least one of information indicating atraveling direction of the moving body and information indicating adirection in which traveling of the moving body is prohibited.
 11. Theillumination device according to claim 9, wherein the informationindicating a traveling direction of the moving body comprisesinformation on an arrow indicating a traveling direction of the movingbody.
 12. The illumination device according to claim 10, wherein theinformation indicating a traveling direction of the moving bodycomprises information on an arrow indicating a traveling direction ofthe moving body.
 13. The illumination device according to claim 9,wherein the information indicating a direction in which traveling of themoving body is prohibited comprises information on an arrow and an Xmark indicating a direction in which traveling of the moving body isprohibited.
 14. The illumination device according to claim 1, whereinthe second diffusion region displays the information by changing atleast one of hue, brightness, and chroma in the second area.
 15. Theillumination device according to claim 1, wherein the coherent lightsource comprises a plurality of light emitting units that emit aplurality of coherent light beams having different emission wavelengthranges, and at least one of the first diffusion region and the seconddiffusion region has a plurality of diffusion region parts to be scannedby the plurality of coherent light beams.
 16. The illumination deviceaccording to claim 1, wherein the optical device is a hologram recordingmedium, and the first diffusion region and the second diffusion regionhave element hologram areas in which different interference fringepatterns are formed.
 17. The illumination device according to claim 1,wherein the optical device is a lens array group having a plurality oflens arrays, and the first diffusion region and the second diffusionregion comprise the lens arrays.
 18. The illumination device accordingto claim 1, wherein the optical device comprises a hologram recordingmedium and a lens array group having a plurality of lens arrays, and oneof the first diffusion region and the second diffusion region comprisesthe hologram recording medium and another comprises the lens arraygroup.
 19. An illumination system comprising an illumination deviceaccording to claim
 1. 20. A vehicle comprising an illumination deviceaccording to claim 1.